Download - Description of a new species of Aeglidae, and new records of related species from river basins in Argentina (Crustacea, Anomura)

18 Accepted by S. Ahyong: 27 Nov. 2009; published: 25 Jan. 2010

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Zootaxa 2343: 18–30 (2010) www.mapress.com/zootaxa/ Article

Description of a new species of Aeglidae, and new records of related species from river basins in Argentina (Crustacea, Anomura)

GEORGINA BOND-BUCKUP1,5, CARLOS G. JARA2, LUDWIG BUCKUP1,

ALESSANDRA A.P. BUENO4, MARCOS PÉREZ-LOSADA3 & KEITH A. CRANDALL3

1Departamento de Zoologia, Instituto Biociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, 90501-970, Porto Alegre, Brazil2Instituto de Zoología, Casilla 567, Universidad Austral de Chile, Valdivia, Chile.3Department of Integrative Biology, Brigham Young University, Provo UT 84602-5255, U.S.A.4Departamento de Biologia, Universidade Federal de Lavras, São Paulo, Brazil5Corresponding author. E-mail: [email protected]

Abstract

The anomuran crustacean Aegla saltensis new species, from the Province of Salta in northwest Argentina is described and illustrated, and its morphological differences from other related species are discussed. The 13 species that occur in Argentina are analyzed in the light of new available samples. The geographical distributions of the species are updated and new localities are recorded for eight of the thirteen species.

Key words: Aeglidae, diversity, drainage basin, Argentina, new species

Introduction

Aeglid crabs are the only family of anomuran decapods endemic to river basins in Neotropical South America. Collecting efforts in South American aquatic habitats have intensified in the past decade, because of rapid degradation in water quality which has resulted in the disappearance of some species from localities where they had previously been recorded. This has underlined the necessity of improving knowledge of the Neotropical fauna, as a basis for the establishment of public policies for the conservation of waterbodies and their biodiversity.

Within the territory of Argentina, 13 species of aeglids have been recorded by Bond-Buckup & Buckup (1994) : Aegla affinis Schmitt, A. humahuaca Schmitt, A. intercalata Bond-Buckup & Buckup, A. jujuyana Schmitt, A. neuquensis Schmitt, A. platensis Schmitt, A. ringueleti Bond-Buckup & Buckup, A. riolimayana Schmitt, A. sanlorenzo Schmitt, A. scamosa Ringuelet, A. septentrionalis Bond-Buckup & Buckup, A. singularis Ringuelet, and A. uruguayana Schmitt. The present contribution, 14 years after the last revision of the Aeglidae (see Bond-Buckup & Buckup 1994) in Argentinian river basins, has the objective of describing a new species, recording new localities, and providing updated information on species distributions.

Material and methods

The specimens examined were obtained from sampling campaigns in hydrographic basins of Argentina, carried out by the authors in the years 2001, 2003 and 2007, in several watercourses of the provinces of Jujuy, Salta, Catamarca, Tucuman, San Juan, Mendoza, and Buenos Aires. The collections in southern Brazil were made in the last decade by several persons, and records come from the Crustacean Collection of the

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Department of Zoology of the Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. Several scientific collections were reviewed, as listed below.

List of repositories

UFRGS — Departamento de Zoologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; FML — Instituto de Zoologia, Fundación Miguel Lillo, Tucumán, Argentina; MACN — Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina. MZUSP- Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil.

Records of A. affinis and A. neuquensis deposited in the collection of the Instituto de Zoología of the Universidad Austral de Chile (IZUA), Valdivia, Chile, are based on the electronic database of that collection, though the collection was destroyed by a fire on 3 December 2007.

The description of the new species is based on examination of characters of the type series. The methodology adopted to measure the specimens follows Bond-Buckup & Buckup (1994). The following abbreviations are used: CL — carapace length, taken from the apex of the rostrum to the posterior margin of the carapace; AL — areolar length, the length of the median longitudinal line of the areola; AW — areolar width, distance between the lateral margins of the areola, measured from just behind their anterior curvature; FW — frontal width, distance between the tips of the anterolateral spines of the carapace; PCW — precervical width, width of the carapace measured at the level of the third hepatic lobes. In the text, M represents males, F females, F ov ovigerous females, and J juveniles.

Results

The samples collected in Argentina allowed us to identify a new species of aeglid, and to add new records of occurrence, with the respective geographical coordinates, of eight other species.

Aeglidae

Aegla saltensis Bond-Buckup & Jara new species(Fig.1a–e)

Material examined. Holotype: male, Argentina, Province of Salta, Pasaje River at Route 34, 25°07'52"S, 65°00'54"W, 746 M, 08.xii.2001, coll. G. Bond-Buckup, C. Jara, M. Perez-Losada (MZUSP 20466). Paratypes: Argentina, 3 females (UFRGS 3359P), same data as the holotype; Province of Salta, Juramento River below Penas Blancas Reservoir, 13.xii.1984, Grosso, L. col., FML 00490, 1M, 1F.

Diagnosis. Anterolateral spine of carapace extending beyond base of cornea; protogastric lobes absent; extraorbital sinus narrow, V-shaped; rostrum triangular, carinate along its entire length, strongly deflected, proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped without lobular tooth; palmar crest of cheliped absent; anterior angle of ventral margin of epimera 2 unarmed; inner margin of ventral face of ischium of cheliped with one distal spine and a small proximal tubercle; dorsal margin of carpus of second and third pereiopods with one distal spine followed by scale-shaped tubercles.

Description. Carapace moderately convex, area of gastric region elevated, dorsal surface scabrous, covered with small scales and punctations.

Front narrow; PCW/FW ratio of male holotype 1.96.Rostrum triangular, elevated from medial to distal portion, strongly deflected, of medium length, broad at

base and tapered at extremity, indented in middle, carinate to apex. Subrostral process absent; in profile, rostrum with dorsal part higher than ventral part. Rostral carina beginning between protogastric lobes and

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epigastric prominences, with two parallel, closely set rows of pronounced scales that soon after form single row on distal third. Lateral margins of rostrum scaly.

Orbits moderately broad, shallow, bounded externally by small orbital spine. Orbital margin with few scales. Extraorbital sinus narrow, V-shaped.

FIGURE 1. Aegla saltensis new species, male holotype (MZUSP 20466): a, dorsal view; b, pre-cervical portion of carapace, side view; c, inner margin of ischium of cheliped; d, lateral view of second abdominal epimeron; e, third and fourth sterna, ventral view. (Scale: 8 mm).

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Anterolateral angle of carapace projected anteriorly by spine extending beyond base of cornea. Outer margin of anterolateral lobe with scale-shaped tubercles; inner margin unarmed.

First hepatic lobe delimited anteriorly by small fissure; lateral margin with subequal, scale-shaped tubercles; 2nd and 3rd hepatic lobes not delimited, with only modest incision; lateral margins with subequal, scale-shaped tubercles.

Epigastric prominences little defined, low, of indefinite shape, elongated toward base of 1st hepatic lobe, with few scales. Protogastric lobes absent; anterior margin marked only by several scales.

Transverse dorsal line slightly sinuous. Areola subrectangular to rectangular, with margins subparallel in their entire length. AL/AW of male holotype: 1.87.

Epibranchial area triangular, well developed, with one apical tubercle followed by smaller, scale-shaped tubercles. Lateral margins of anterior and posterior branchial area with subequal, scale-shaped tubercles.

Anterior angle of ventral margin of epimera 2 unarmed; ventrolateral margin slightly convex; posterior angle of ventral margin unarmed (Fig.1d). Epimera of 3rd to 6th segments produced; lateral projection on 3rd and 4th ornamented with small apical tubercle.

Telson divided by longitudinal sulcus.Anterior extremity of third sternite truncate, projecting between coxae of exopodites of third maxillipeds.

Fourth thoracic sternite flat, lateral margins not recurved; Anterolateral margin projecting, with one tubercle; tuft of long setae, transversely on anterior part of segment (Fig.1e).

Cheliped unequal, hand subrectangular. Major cheliped globose, palm inflated in posterolateral region, covered by corneal scales. Minor cheliped more tapered. Palmar crest absent. Pre-dactylar lobe forming small step with anterior margin of propodus. Fingers thickened and covered with scales. Proximal outer margin of moveable finger without lobe. Prehensile margins of fingers with scale-shaped denticles along their entire length, however without opposing, dovetailed lobular teeth, with a space between the teeth. Dorsal face of carpus rugose, with scales; inner margin with three to four spines, distal spine most robust of the group; these spines with a few spinules on lateral margins; inner anterolateral angle subobtuse, with apical tubercle; anterodorsal margin with scales. Carpal crest modestly pronounced, especially at proximal region, with scales in groups of three to five on elevations of crest; crest absent in distal region, with few scales; outer ventral angle of carpus with one spine; ventral face with one conical spine. Dorsal margin of merus of cheliped with one, more-pronounced distal spine, remaining margin with scale-shaped tubercles; anterodorsal margin with scales. Lateral faces scabrous, with scales. Inner ventral margin of merus with one distal spine and several smaller tubercles; outer ventral margin with prominent distal tubercle, followed by scale-shaped tubercles (Fig.1c). Dorsal margin of ischium with elevation ornamented with scales; inner margin of ventral face with one, more-prominent distal spine, and two or three smaller tubercles arranged along the margin.

Dorsal margin of dactylus, propodus, and carpus of 2nd, 3rd, and 4th pereiopods with longitudinal rows of scales. Carpus of 2nd and 3rd pereiopods armed anterodorsally with one scale-shaped tubercle.

Variations. The three female paratypes have more prominent spines. On the proximal outer margin of the moveable finger there are several scales, suggesting the presence of a lobe. The anterior margin of the propodus of the paratypes has a strong spine followed by several tubercles ornamenting the region of the palmar crest, without, however, constituting a palm.

Measurements. Male holotype 29.1 mm CL. Mean of paratypes 21.1 mm CL (n = 5 (1M, 4 F).PCW/FW ratios of paratypes ranging from 1.89–2.11, mean 2.05. AL/AW ratios of paratypes ranging

from 1.52–1.90, mean 1.76.Distribution. ARGENTINA: Parana River system - Province of Salta, Pasaje River or Juramento River.Discussion. The new species, Aegla saltensis, is quite close to Aegla jujuyana Schmitt, sharing the

absence of a proximodorsal lobe on the moveable finger and a lobular tooth on the cutting edge of cheliped, thus with palmar crest absent. It is distinguished from A. jujuyana by the more globose hand; by the definition of the pre-dactylar lobe of the cheliped, by the longer rostrum, by the presence of the carpal crest, and by the absence of ornamentation on the anterior angle of the ventral margin of epimera 2. Although the shape of the rostrum is similar in both species, that of A. saltensis is much more deflected, comparable in this respect only



to that of the Brazilian species A. obstipa. The globose major cheliped, with the palm inflated in the posterolateral region, is similar to that of A. septentrionalis and A. affinis; however, these have the rostrum lingulate, much different from the new species.

One of the most marked characters of A. saltensis, the absence of the palmar crest, is uncommon in aeglids, occurring only in A. jujuyana, A. uruguayana, A. marginata, and A. septentrionalis. These latter three species, however, do not share other characters with the new species.

Biology: Unknown. Etymology: Named in honor of Salta Province, the type locality.

Aegla affinis Schmitt, 1942

Diagnosis. Anterolateral spine of carapace reaching middle of cornea; protogastric lobes absent; transverse dorsal line sinuous; extra-orbital sinus absent; rostrum of medium length, lingulate; rostrum with carina little evident in distal third; front narrow; fourth thoracic sternite with several scales; proximal outer margin of moveable finger of cheliped without lobe; palmar crest very modest; inner margin of ventral face of ischium of chelipeds with at most six tubercles; ventral margin of merus of second pereiopod with scale-shaped tubercles. (Modified from Bond-Buckup & Buckup 1994)

New records. ARGENTINA: Province of Mendoza: Tunuyán River below El Carrizal Reservoir, Province of Mendoza, 33º17'53"S, 68º43'12"W, 740 m, 01.x.2006 (IZUA 879, 1 M, 14 F); Arroyo Claro, extreme northern part of city of Tunuyán, Province of Mendoza, 33º33'56"S, 69º01'01"W, 862 m, 01.x.2006 (IZUA 880, 7M, 1F); Atuel River, upstream from El Nehuil Reservoir, 35º05'07"S, 68º50'59"W, 1300 m, ix.2006 (IZUA 881, 1M); Chico River, tributary of the Colorado River, Malargüe, 20.ii.2000 (UFRGS 2983, 2M, 3F). CHILE: Province of Talca: Source of Maule River in Laguna Del Maule, Talca, 19.xii.2000 (UFRGS 2984, 2M, 2F); Small lagoon in Rio Maule, 5 km downstream from Laguna del Maule, Talca, 20.xii.2000 (UFRGS 2985, 3M, 1F).

Former distribution. ARGENTINA: Central and southwestern part of Province of Mendoza, and northern part of Neuquén. CHILE: Provinces of Santiago [? or Cachapoal?] and Linhares (Bond-Buckup & Buckup 1994). Laguna Del Maule (Bahamonde et al. 1998).

Present distribution. ARGENTINA: Colorado River system — Central and southern Province of Mendoza, northern Neuquén. CHILE: Provinces of Santiago [? or Cachapoal?], Linhares, and Talca.

Aegla humahuaca Schmitt, 1942

Diagnosis. Anterolateral spine of carapace not reaching base of cornea; protogastric lobes absent; rostrum short, strongly deflected; rostrum carinate along its entire length; front narrow; proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped without lobular tooth; palmar crest of cheliped little developed, rectangular, short; inner margin of ventral face of ischium of cheliped with one anterior conical spine and up to four tubercles; dorsal margin of merus of second pereiopod with scale-shaped tubercles. (Modified from Bond-Buckup & Buckup 1994.)

New records. ARGENTINA: Province of Tucumán: River near to San Pedro de Colalao. 26º14'27"S, 65º9'35"W; 1118m, 09.xii.2001 (UFRGS 3230, 4M, 1F); Loc.Rio Noque, La Cascada, La sala Sr. Javier, FML 00150 (together with A. platensis); Provínce of Catamarca: Loc. Junca-Suma, River Potrero, xi.1967 (FML s/n). Former distribution. ARGENTINA: Central and southern Province of Jujuy, northwestern, central, and southern Salta, northern and central Tucumán, northwestern Santiago del Estero (Bond-Buckup & Buckup 1994).



Present distribution. ARGENTINA: Parana River system - Bermejo, Dulce, Juramento, and Grande rivers - central and southern Jujuy, northwestern, central, and southern Salta, northern and central Tucumán, western Catamarca, northwestern Santiago del Estero.

Remarks. The localities in the drainage basins of Tucumán and Catamarca provinces are new records, and broaden the geographical distribution of A. humahuaca..

Aegla intercalata Bond-Buckup & Buckup, 1994

Diagnosis. Anterolateral spine of carapace reaching base of cornea; protogastric lobes moderately distinct; rostrum of medium length, indented; rostrum carinate along its entire length; front narrow; anterior angle of ventral margin of epimera 2 unornamented or with one or more scales; proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped with lobular tooth; palmar crest of cheliped absent or slightly developed; inner margin of ventral face of ischium of cheliped with four prominent tubules, and smaller tubercles among them; ventral margin of merus of second pereiopod with scale-shaped tubercles. (Modified from Bond-Buckup & Buckup 1994.)

New records. ARGENTINA: Province of Tucumán: stream of River Los Sojas, with Ruta 307, direction to Tucumán with Tafi del Valle, 26º56'27"S, 65º9'56"W; 1855 m, 10.xii.2001 (UFRGS 3228, 1 F); Stream at 15 km Taffi del Valle, Las Carreras. 26º56'00"S, 65º46'33"W; 2366 m, 10.xii.2001 (UFRGS 3226, 3 M, 2 F); id., ib. (UFRGS 3229, 3 M, 4F); Stream tributary, direction Concepción to El Clavillo. 27º21'30"S, 65º49'05"W; 655m, 11.xii.2001 (UFRGS 3224, 4 M, 1 F); Province of S. F. Catamarca: River Las Trancas, Las Juntas, near El Rodeo, Catamarca. 28º04'27"S, 65º54'25"W; 1485m, 11.xii.2001 (UFRGS 3225, 1 M 4 F).

Former distribution. ARGENTINA: Northwestern Tucumán, southeastern and eastern Catamarca (Bond-Buckup & Buckup 1994).

Present distribution. ARGENTINA: Mar Chiquita system – Dulce River – northwestern and southwestern Tucumán, southeastern and eastern Catamarca.

Remarks. The specimens of Aegla intercalata were collected in different habitats, in silt or under rocks, in river backwaters and also where the current was swift. The new records are within the geographical distribution already known for this species.

Aegla jujuyana Schmitt, 1942

Diagnosis. Anterolateral spine of carapace exceeding half of cornea; protogastric lobes obsolete; rostrum short, narrow, deflected; rostrum carinate along its entire length; front narrow; proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped without lobular tooth; palmar crest of cheliped absent; inner margin of ventral face of ischium of cheliped with tubercles; areola rectangular. (Modified from Bond-Buckup & Buckup 1994.)

Measurements. Mean length of cephalothorax: 23.13 mm CL (n = 4 males). The PCW/FW ratio confirms the narrow front and the rectangular areola as characterized by Bond-Buckup & Buckup (1994). Examination of new specimens and new comparative analyses, relating the length of the rostrum to the length of the cephalothorax from the orbit, characterized the rostrum of A. jujuyana as short. Therefore, this character modifies the species diagnosis given by Bond-Buckup & Buckup (1994).

New records. ARGENTINA: Province de Jujuy: catchment near Escuela Agrotecnica, locality of Humahuaca. 23º11'50"S, 65º20'25"W; 2998 m, 05.xii.2001 (UFRGS 3206, 3M, 2F); Lagon at North of Tilcara, side to Rio Grande, Tilcara. 23º33'50"S, 65º23'05"W; 2503 m, 05.xii.2001 (UFRGS 3211, 11M, 4F, 4J).

Former Distribution. ARGENTINA: Provinces of Jujuy and northeastern Salta (Bond-Buckup & Buckup, 1994).



Present distribution. ARGENTINA: Paraná River system, Grande River, Provinces of Jujuy and northeastern Salta.

Remarks. The site where the specimens were found, a reservoir in Humahuaca, with a silty bottom and input of oxygen through upwelling from the subsoil, was unprecedented, because the species has until now been recorded in fast-flowing rivers.

Aegla neuquensis Schmitt, 1942

Diagnosis. Anterolateral spine of carapace not reaching base of cornea; protogastric lobes absent; transverse dorsal line straight; rostrum of medium length, linguiform, carina absent on distal third; front narrow; fourth thoracic sternite elevated medially, with scale; proximal outer margin of moveable finger of cheliped with lobe; palmar crest subrectangular, margin indented; inner margin of ventral face of ischium of cheliped with two spines and up to three tubercles (Bond-Buckup & Buckup 1994).

New records. ARGENTINA: Province of Neuquen, River Malleo, Junin de Los Andes, 39º50'1.4"S, 70º55'28.3"W; 718 m, 28.iii.2007 (UFRGS 4408, 8M, 2J); River Neuquen, downstream of Ing. Ballester dam, 38º43'40"S, 68º10'23"W, 308 m, 03.ii.2006 (IZUA 862, 5F, 25M); River Molulco at El Alamito, Chos Malal, 37º15'20"S, 70º25'14"W, 1048 m, 04.ii.2006 (IZUA 863, 22F, 20M); River Collón Cur at La Rinconada, close to bridge, 39º59'49"S, 70º50'08"W, 655 m, 04.ii.2006 (IZUA 864, 5F, 4M). Province of Chubut, River Mayo at Paso Mayo, 45º40'56"S, 70º15'55"W, 427 m, 31.i.2006 (IZUA 858, 21F, 4M); River Senguer next to Musters lake, 45º35'54"S, 69º10'57"W, 278 m, 31.i.2006 (IZUA 859, 8F, 34M); River Chubut at Los Altares, 43º51'17"S, 68º49'04"W, 284 m, 01.ii. 2006 (IZUA 860, 11F, 11M); River Chubut at Leleque, 42º24'41"S, 71º04'25"W, 670 m, 02.ii.2006 (IZUA 861, 22F, 14M). CHILE: Province of Aysén, River Blanco at El Blanco Coyhaique, 45º48'24"S, 71º54'57"W, 462 m, 28.i.2006 (IZUA 857, 8F, 22M).

Former distribution. ARGENTINA: Provinces of Neuquén, Río Negro, southern Buenos Aires, and Chubut (Bond-Buckup & Buckup, 1994). CHILE: Cuenca R. Simpson, Coyhaique, Aysén (Bahamonde et al.1998).

Present distribution. ARGENTINA: Patagonian River systems — Provinces of Neuquén, Río Negro, southern Buenos Aires, and Chubut. CHILE: Cuenca R. Simpson (Bahamonde et al. 1998).

Aegla platensis Schmitt, 1942

Diagnosis. Anterolateral spine of carapace reaching half of cornea; protogastric lobes moderately raised; rostrum very long in adults, carinate along its entire length; anterior angle of ventral margin of epimera 2 with spine; fourth thoracic sternite raised medially, with scale; proximal outer margin of moveable finger of cheliped bearing lobe with tubercle; palmar crest rectangular, little developed; inner margin of ventral face of ischium unornamented (Bond-Buckup & Buckup 1994).

New records. ARGENTINA: Province of Tucumán: River Las Tiapas and Los Membrillos with Ruta

341, 26º 51'19"S, 65º25'51"W; 707 m, 09.xii.2001,( UFRGS 3231, 2 M); Loc.Rio Noque, La Cascada, La sala Sr. Javier, FML 00150 (togheter with A. humahuaca).

Former distribution. ARGENTINA: Northern and central Province of Buenos Aires, eastern Tucumán, southeastern Catamarca, and southwestern Misiones. BRAZIL: Southwestern Santa Catarina, and Rio Grande do Sul, except its northeastern part. PARAGUAY: Colonia Independencia. URUGUAY: Departments of Colonia and Canelones (Bond-Buckup & Buckup 1994).

Present distribution. ARGENTINA: Paraguay River system, Mar Chiquita system, Dulce River – central Province of Buenos Aires (?), eastern Tucumán, southeastern Catamarca, and southwestern Misiones. BRAZIL: Southwestern Santa Catarina, and Rio Grande do Sul except its northeastern part. PARAGUAY:Colonia Independencia. URUGUAY: Departments of Colonia and Canelones.



Remarks. Bond-Buckup & Buckup (1994) identified lots MACN 20959-1, 11857, 23171, and 25931, all from the La Plata River, as A. platensis. However, the first author, during a recent revision of the MACN collection, determined that these specimens are not A. platensis, but another, very similar species. In sampling in tributaries along the right bank of the La Plata River, Province of Buenos Aires, only A. uruguayana was recorded, corroborating the absence of records of A. platensis from the watercourses located in northern Buenos Aires Province. This resulted in changes in its geographical distribution in Argentina, in addition to the new records from the Province of Tucumán. There still remain doubts as to the statement of Schmitt (1942), who mentioned in his description of A. platensis that the lot was collected on “Isla Flores, which may equally be located near Buenos Aires or in the Department of Canelones in Uruguay.

Aegla platensis has been used as an experimental model in the laboratory as well as in the field (for a review see Bueno & Bond-Buckup 2000; Bueno et al. 2000; Bueno & Bond-Buckup 2004; Ferreira et al. 2005; Oliveira et al, 2007; Almerão et al. 2007).

Aegla ringueleti Bond-Buckup & Buckup, 1994

Diagnosis. Anterolateral spine of carapace reaching base of cornea; protogastric lobes absent; rostrum triangular, of medium length, carinate along its entire length; front narrow; anterior angle of ventral margin of epimera 2 with small tubercle; fourth thoracic sternite raised, with tubercle; proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped without lobular tooth; palmar crest of cheliped little developed, narrow; inner margin of ventral face of ischium of cheliped with up to three tubercles; dorsal margin of merus of second pereiopod unornamented, with long setae; ventral margin of merus of second pereiopod with scale-shaped tubercles; inner margin of coxa of cheliped with one conical spine. (Modified from Bond-Buckup & Buckup 1994.)

Measurements. Mean length of cephalothorax: 23.19 mm CL (n = 3 males); 21.69 mm CL (n = 4 females). The mean of the PCW/FW ratio (2.04) confirms the narrow front; however, the areola is quadrate (mean AL/AW=1.49 for males and 1.56 for females). Examination of new specimens and new comparative analyses led to modifications in the species diagnosis of Bond-Buckup & Buckup (1994).

New Records. ARGENTINA: Province of Salta, River Calchaqui, near city Cachi. 25º07'16"S, 66º09'31"W; 2346 m, 07.xii.2001 (UFRGS 3207, 12 M, 12 F).

Former distribution. ARGENTINA: Province of Salta, Cachi.Present distribution. ARGENTINA: Parana River system, Salado River.Remarks. Aegla ringueleti was described by Bond-Buckup & Buckup (1994) on the basis of only two

females, that were deposited in the Senckenberg-Museum, Frankfurt, Germany (SMF). The collection records indicated an altitude of 4500 m. However, the locale where this species was found is quite singular, at a lower altitude than previously recorded, a mountain river with variable water volume. These streams become torrents during the spring melt, and contain little water during the rest of the year. A large population of the species was found, most of medium size, with a few large specimens. The watercourse was more than 20 m wide, only about 20 cm in depth, and had a rocky bottom, with the animals concentrated along the riverbanks. This river, embedded in the Andes, shelters the species that is the most basal ingroup taxon (Perez-Losada et al. 2004), suggesting that A. ringueleti became trapped in the Andes during their uplifting about 65 my ago.

Aegla riolimayana Schmitt, 1942

Diagnosis. Anterolateral spine of carapace not reaching basis of cornea; posterior margins of areola convergent; rostrum of medium length in adult males, styliform, carinate along its entire length; front wide, anterior angle of ventral margin of epimera 2 with small spine; outer proximal margin of moveable finger of cheliped with rudimentary lobe; palmar crest present, subrectangular, indented, with tubercles; inner margin



of ventral face of ischium of cheliped with only two tubercles; dorsal margin of merus of second pereiopod unornamented, with setae. (Modified from Bond-Buckup & Buckup 1994.)

New records. ARGENTINA: River Chimehuin, Junin de Los Andes, 39º59'17"S, 71º3'36.2"W; 776m, 26.iii.2007 (UFRGS 4407, 1M, 15F).

Former distribution. ARGENTINA: Western and southern Province of Neuquén. CHILE: Southern Province of Cautin; Provinces of Valdivia, Osorno, and Llanquihue; and Chilóe Island (Bond-Buckup & Buckup 1994; Bahamonde et al.1998).

Present distribution. ARGENTINA: Patagonian River systems in Neuquén Province. CHILE: Province of Valdivia (only in the basin of the San Pedro River - Calle Calle); Osorno: Lake Puyehue; Chilóe Island.

Aegla sanlorenzo Schmitt, 1942

Diagnosis. Anterolateral spine of carapace reaching distal part of cornea; protogastric lobes raised; rostrum long, acuminate, deflected; rostrum carinate along its entire length; anterior angle of ventral margin of epimera 2 with acute spine; proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped without lobular tooth; palmar crest of cheliped absent; inner margin of ventral face of ischium of cheliped with only two, robust spines; ventral margin of merus of second pereiopod with distal spines followed by tubercles (Bond-Buckup & Buckup 1994).

Measurements. The specimens examined showed a mean CL of 19.21 mm (n = 9 males); 17.22 mm (n = 7 females). Rostrum long. PCW/FW ratio ranging from 1.60 to 1.92, with a mean of 1.78 for males and 1.81 for females; i.e., a wide front. AL/AW ratio ranging from 1.49 to 1.89, mean 1.67 for males and 1.54 for females; i.e., areola quadrate to subquadrate.

New records. ARGENTINA: Province of Salta: watercourse Los Berros, with bridge Ruta 34, near to

Calikuala. 23º 44'51"S, 64º 39'57"W; 392 m, 06.xii.2001 (UFRGS 3212, 3M, 2F); Province of Salta: Canal with Ruta 50, direction to San Ramon de La Nueva Oran, locality of Hipolito Irigoyen. 23º14'28"S, 64º16'29"W; 321m, 06xii.2001 (UFRGS 3214, 2 M, 2 F., 2 J).

Former distribution. ARGENTINA: Province of Jujuy, San Lorenzo River (Bond-Buckup and Buckup 1994).

Present distribution. ARGENTINA: Parana River - Bermejo River system in the provinces of Salta and Jujuy.

Remarks. Bond-Buckup and Buckup (1994) raised doubts as to the status of A. sanlorenzo, considering that only the type was known. It is deposited in the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia in Buenos Aires (MACN 7099).

The region of the type-locality has a very dry climate with a large moisture deficit, which was confirmed in the course of sampling at that location (23º43'56"S, 64º44'33"W; 478 m altitude). No specimens of A. sanlorenzo were found, because of the small amount of water in the river. However, the species was found in the Province of Salta, a new locality record. At Arroyo Los Berros in Jujuy Province, the river was flowing slowly, with its rocky banks silted over with extensive deposits of mud, in which the specimens were buried.

Aegla scamosa Ringuelet, 1948

Diagnosis. Anterolateral spine of carapace reaching and sometimes exceeding base of cornea; protogastric lobes absent; transverse dorsal line sinuous; rostrum triangular, of medium length, carinate with indistinct scales on the distal third; front narrow; anterior angle of ventral margin of epimera 2 with two or more scales; fourth sternite slightly raised, medially, with scale; proximal outer margin of moveable finger of cheliped without lobe; palmar crest present, sub-rectangular, indented; inner margin of ventral face of ischium of cheliped only with five tubercles; dorsal and ventral margins of merus of second pereiopod with scale-shaped tubercles and scales. (Modified from Bond-Buckup & Buckup 1994).



Measurements. The specimens examined showed a mean CL of 24.04 mm (n = 8 males; 1 female). Species with rostrum of medium length, which modified the species diagnosis of Bond-Buckup & Buckup (1994). PCW/FW ratio ranging from 1.90 to 2.12, mean 1.97; i.e., a narrow front. AL/AW ratio ranging from 1.52 to 1.85, mean 1.61; areola subquadrate.

New records. ARGENTINA: Province of Mendoza: Rio Mendoza, with Ruta 7, near to 10 km of Upslatta. 32º41'24"S, 69º21'37"W; 1709 m, 01.xii.2001 (UFRGS 3217, 4M, 2F, 1J); Frei L. Beltran, Finca Gune, Mendoza, 27.ii.1942 (MLP 0086, 1M, 2F); Province of San Juan: watercourse of Água Negra, tributary of River Jachal, with Ruta 40, at 7 km of San Juan, San Juan Jachal. 30º19'59"S, 68º42'39"W; 1086 m, 02.xii.2001 (UFRGS 3215, 2M, 3F, 6J); idem, ibidem (UFRGS 3216, 1M, 4F); River Jachal, near to Ruta 150, with S.J. Jachal and Rodeo. 30º12'52"S, 69º02'14"W; 1476 m, 02.xii.2001 (UFRGS 3223, 3M, 2F).

Former distribution. ARGENTINA: Southern San Juan Province, northwestern Mendoza Province (Bond-Buckup & Buckup 1994).

Present distribution. ARGENTINA: Colorado River system in the provinces of San Juan and Mendoza.Remarks. The localities in San Juan Province are new records, and enlarge the geographical distribution

of this species.

Aegla septentrionalis Bond-Buckup & Buckup, 1994

Diagnosis. Anterolateral spine of carapace reaching half of cornea; protogastric lobes absent; extra-orbital sinus absent; rostrum of medium length, linguiform, with little-pronounced carina on distal third; front narrow; anterior angle of ventral margin of epimera 2 unornamented; fourth thoracic sternite without ornament, flat; outer proximal margin of moveable finger of cheliped without lobe; fingers of cheliped with robust lobular tooth; palmar crest of cheliped absent; inner margin of ventral face of ischium of cheliped only with three to four nodosities. (Modified from Bond-Buckup & Buckup 1994.)

Measurements. The specimens examined showed a mean CL of 18.90 mm (n = 8 males; 5 females). Rostrum of medium length, which modifies the species diagnosis given by Bond-Buckup & Buckup (1994). PCW/FW ratio ranging from 1.81 to 1.99, mean 1.94; i.e., front narrow. AL/AW ratio ranging from 1.60 to 1.73, mean 1.68; areola subquadrate.

New records. ARGENTINA: Province of Jujuy: Arroyo Cangrejillos, basin of River Miraflores, 22º24'33"S, 65º34'14"W; 3613 m, 05.xii.2001 (UFRGS 3205, 4M, 1F); id., ib., UFRGS 3208, 11M, 6F, 6J); Yavi, northewest Argentina, 06.i.1994 (UFRGS 2431, 3M, 1F).

Former distribution. BOLIVIA: Departments of Tupiza and Tarija. ARGENTINA: Northern parts of Jujuy and Salta provinces (Bond-Buckup & Buckup 1994).

Present distribution. BOLIVIA and ARGENTINA - Paraguay River system (Bermejo and Pilcomayo rivers).

Remarks. The locality of Cangrejillos, at an altitude of 3613 m, is the highest altitude recorded up to now for a species of aeglid.

This pre-cordilleran region is in the Bolivian altiplano, with an arid climate, strong winds, and a large moisture deficit. The species was collected in a small stream, in the middle of a site with grassy vegetation. Although the locale was uncharacteristic for an aeglid, because of the small volume of water, the population was numerous, and composed of specimens of several age classes.

Aegla singularis Ringuelet, 1943

Diagnosis. Lateral margins of anterior branchial area of carapace with scale-shaped tubercles; anterolateral spine of carapace reaching half of cornea; epigastric prominences absent; protogastric lobes raised; rostrum long, styliform, carinate along its entire length; front wide; anterior angle of ventral margin of epimera 2



projecting as a spine; fourth thoracic sternite raised, with scale; proximal outer margin of moveable finger of cheliped with lobe tipped by a robust spine; anterolateral angle of carpus of cheliped acute and projecting in a spine bent toward the carpo-palmar joint; palmar crest rectangular, with lobes and spines; inner margin of ventral face of ischium of cheliped with one distal spine and up to two medial tubercles; dorsal margin of merus of second pereiopod with tubercles and scale-shaped tubercles. (Modified from Bond-Buckup & Buckup 1994.)

Measurements. Males with mean CL of 22.18 mm (n = 7); females with mean CL of 23.73 mm (n = 10 males), showing a mean size much larger than that given by Ringuelet (1948). Species with long rostrum. PCW/FW ratio ranging from 1.61 to 1.87, with a mean of 1.74 in males and 1.67 in females; i.e., front wide. AL/AW ratio from 1.69 to 2.10; mean 1.90 in males and 1.89 in females; areola rectangular.

Former distribution. ARGENTINA: Province of Misiones (Bond-Buckup & Buckup 1994). Present distribution. ARGENTINA, BRAZIL, URUGUAY- Basin of Uruguay River.Remarks. There are no new records for watercourses within Argentina. However, this species was found

in southern Brazil and northern Uruguay in tributaries in the Uruguay River drainage basin (Bond-Buckup etal., not published).

Aegla uruguayana Schmitt, 1942

Diagnosis. Anterolateral spine of carapace exceeding half of cornea; rostrum long, tending toward styliform, carinate along its entire length; anterior angle of ventral margin of epimera 2 projecting as a spine; fourth thoracic sternite raised, with a spine; proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped with lobular tooth; palmar crest of cheliped absent; inner margin of palm broadly carinated, armed anteriorly with a sharp spine; inner margin of ventral face of ischium of cheliped with one distal robust spine and up to three elevations along the segment; dorsal margin of merus of second pereiopod with a distal spine and scale-shaped tubercles; ventral margin of merus of second pereiopod with scales (Modified from Bond-Buckup & Buckup 1994).

New records. ARGENTINA: Province of Buenos Aires: River Areco, basin River La Plata, Carmen de Areco. 34º24'46.8"S, 59º57'41.7"W; 44 m, 21.x.2003 (UFRGS 3655, 5M, 1F); Tributary of River Dulce, bridge with Ruta 191, Basin River La Plata, near Salto. 34º20'14.4"S, 60º16'55.5"W; 58 m, 21.x.2003 (UFRGS 3656, 13M, 9F); Arroyo Cepeda with Ruta in direction to Mariano Benitez, Basin of River La Plata. 33º41'47.2"S, 60º 31'55.9"W; 69 m, 21.x.2003 (UFRGS 3658, 3J, 7M, 12F); Arroyo Manantiales, Basin of River La Plata, loc. Pergamino, deviation Ruta 188, 33º50'8.9"S, 60º23'13.1"W; 61 m, 22.x.2003 (UFRGS 3662, 3M, 2 F, 8J); Arroyo Manantiales, basin River La Plata, loc. Guerico. 33º42'14" S, 60º20'31.1"W; 51 m, 22.x.2003 (UFRGS 3664, 4 F, 3J); River Areco, basin River La Plata basin, loc. San Antonio de Areco.

34º14'24.7"S, 59º 28'6.2"W; 24 m, 23.x.2003 (UFRGS 3667, 6M, 7F).; Cañada Honda with ruta 41, loc. San Antonio Areco, 34º04'17.8"S, 59º30'26"W; 21 m, 22.x.2003 (UFRGS 3668, 1 M, 1F, 5J).

Former distribution. ARGENTINA: Provinces of Mendoza, San Luis, Cordoba, Santa F, Entre Rios, and Buenos Aires. BRAZIL: southern part of Rio Grande do Sul. Uruguay: Departments of Salta, Paysand, Soriano, Colonia, Rocha, Maldonado, and Canelones (Bond-Buckup & Buckup 1994).

Present distribution. ARGENTINA: Parana River delta, Uruguay River system; La Plata River system and Buenos Aires Province to Colorado River; Pampean System.

Southern BRAZIL, URUGUAY: Uruguay River basin.Remarks. The occurrence of A. uruguayana in the tributaries of the right bank of the La Plata River

corroborates the distribution of this species in northern Buenos Aires Province. The broad geographical distribution of Aegla uruguayana has led to research on this species, particularly

on aspects of its reproduction (see López-Greco et al. 2004; Perez-Losada et al. 2004; Viau et al. 2006).



Evolutionary relationships

The evolutionary relationships among the 13 Argentinean Aegla freshwater crabs have been previously studied by our group (Pérez-Losada et al. 2004). All the phylogenetic analyses showed that although Aegla is monophyletic overall, Argentinean aeglids are polyphyletic: A. ringueleti and A. scamosa were at the base of the trees (45–50 mya), A. affinis and A. riolimayana clustered with the Chilean aeglids from clades A (42.5 +2.6 mya) and B (41 + 1.5 mya), respectively, and A. saltensis, A. humahuaca, A. intercalata, A. jujuyana, A. platensis, A. sanlorenzo, A. septentrionalis, A. singularis, and A. uruguayana were grouped with the Brazilian aeglids forming clade D (25.1 + 0.9 mya). Argentinean aeglids occupy a more or less intermediate position between their Chilean and Brazilian relatives, which agrees with the longitudinal pattern (West to East) of speciation suggested for the entire Aegla group (Pérez-Losada et al. 2004).

Acknowledgements

The author (GBB) thanks to Dr. Enrique Rodrigues and Dr Laura Lopez-Greco, from Laboratory of Experimental Biology, Department of Biodiversity, University of Buenos Aires, Argentina, for assisting with Aegla uruguayana sample collection.

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