Zoologica Scripta, Vol. 20, No. 3, pp. 215-220, 1991 Printed in Great Britain

030&3256/91 $3.00 + .OO Pergamon Press plc

0 1991 The Norwegian Academy of Science and Letters

Two new species of Achaeta (Enchytraeidae, Oligochaeta) from meadow and pasture soils of Germany

MICHAEL HECK and JOERG ROMBKE

Accepted 4 October 1990

Heck, M. & Rombke, J. 1991. Two new species of Ackaeta (Enchytraeidae, Oligochaeta) from meadow and pasture soils of Germany.-Zool. Scr. 20: 215-220.

Two new, closely related species of the genus Ackaeta, A. urbana sp.n. and A. microcosmi sp.n., (Enchytraeidae, Oligochaeta) from meadow and pasture soils of Berlin and Frankfurt (Germany) are described. Both show the same form and length/width ratio of the seminal funnel and the same general shape of the spermathecal system. They are distinguishable by distributions of epidermal sacs: only dorsal (A. microcosmi) or dorsal and ventral (A. urbana). Also the origin of the dorsal blood vessel is different.

M . Heck, FU Berlin, Institut fur Bodenzoologie, Tietzenweg 8547, 0-1000 Berlin 45, Germany 1. Rombke, Battelle Institut, Abt. 312, A m Romerkof 35, 0-6000 Frankfurt 90, Germany.

Introduction

During ecological investigations on the soil fauna of meadows in the vicinity of Frankfurt (Knacker et al. 1988) and Berlin (Heck pers. obs.) several enchytraeid species were found. Two of these species are new to science, both of the genus Achaeta. This genus, today with 23 species of which most have a limited distribution, is known world- wide (Christoffersen 1979). According to Coates (1989) it is one of the few monophyletic enchytraeid genera, but many species descriptions show considerable deficien- cies. Here, we describe two new species, but no revision of the genus is intended. The descriptions arc made using mainly the specific criteria introduced by Nielsen & Chris- tensen (1959, 1961, 1963) and adopts their definition of

spa spermatheca (ampulla) spe spermatheca (ectal part) SP‘ sperm sv seminal vesicle

ventral follicle vf

For segment numbers roman capitals are used

Systematics

Subclass Oligochaeta Family Enchytraeidae Subfamily Achaetinae

Achaeta microcosmi sp.n. (Fig. 1) the genus.

Type material. 1 holotype (ZMUM 01 13528) from Frankfurt (Ger- many), district of Harheim (113 m above sea-level), uncultivated apple orchard, with pasture between the tree lines; between the villages of Harheim and Nieder-Eschbach. From parabrown soil, very loamy silt soil, pH 5.52 (KCI), 2.13 % organic matter. Collected, in summer and autumn 1988, with soil corer (diameter 5.6 cm) and cxtracted with water extraction according to O’Connor (1955), modified after Heitkamp & Schauermann (1982) and Graefe (1984). Nine paratypes (ZMUM

Etymology. The name refers to the place where it was found first: in

Material and methods

The triethanol- amine, 7 mi formaldehyde, 91 ml aqua demin.). Some specimens were fixed in Bouin’s, stained with Borax carmine and mounted on slides in

refer to live specimens. Freehand drawings were made from living,

cal Museum of the University of Hamburg (ZMUM).

were studied alive, fixed and stored in TAF (2

Canada balsam. The measurements of the worms (length, width etc,)

sexually mature worms, Type specimens are depositedwith the Zoologi-

13529) from Same locality. Ten specimens measured.

microcosms (diameter l8 cm, height 60 cm) at the type locality.

Description Abbreviations used in the figures

br brain cc chloragogen cell dbv df dorsal follicle

pulsating expansion of dorsal blood vessel

oesophagus granulated cell hyaline interspaces oesophageal appendages penial bulb (a : ventral view, b: lateral view) pharynx sperm funnel septa1 gland

Small to medium-sized species, about 8 mm long, with a diameter of about 0.35 mm, 33-44 segments (average 38). Preclitellar body brownish due to the large brown ampul- lae of the spermathecae. About 7 rows of cutaneous glands per segment, usually only one row clearly observ- able.

Setae absent. Dorsal (about 70pm long) epidermal sacs present (Fig. 1A) Clitellum extends over segment XII; as in the other species of the genus it is covered by regular transverse rows of granulated gland cells (about 20),

215 Zoologica Scripta 20

216 M . Heck and J . Rombke

G

cc dbv os cc es

Pb

hs

F

Fig. 1 . Achaeta rnicrocosmi sp.n.-A. Anterior part of the body and main characters.-B. Spermatheca (ectal part) with sperm.-C. Sperm funnel.-D. Coelomocytc (a: total view, h: lateral view).-E. Nephridium (preclitellar).-F. Segments IV-VI (a : lateral view, h: dorsal view).-G. Clitellum (ventral view) with (i) granulated cells, (ii) hyaline interspaces, and (iii) areas without visible clitellar glands.-H. Penial bulbus.

Zoologica Scripta 20

Two new species of Achaeta from Germany 217

missing on the ventral side; additionally hyaline gland cells form dorso-lateral longitudinal rows usually the same size as granulated clitellar cells (Fig. 1G). Three

Moller 1971; pers. obs.) and is therefore of restricted taxonomic value.

- ~I

pairs of large septal glands, all united dorsally; all three Ecology. The species was found in a pasture soil at the type locality between the organic layer and the mineral horizon. Like most of the

pairs with lobes; postseptal lobes in and other members of the genus it seems to prefer deeper soil layers around VI (Fig. 1A). Chloragogen cells present from VII as a 5-15 cm. A mixture of amorphous humus and mineral grains corre- dense layer; single cells beginning in IV; cells show many sponding to the habitat of the worms was found in the alimentary canal.

Other enchytraeids found at the type locality belonged to the genus oesophageal Fridericia (e.g. F. galba and F. bisetosa). The mean density in 1988 was

atmendages in V: about 1/4 of the diameter of the worm 23.000 and in 1989 35,000 enchvtraeids Der sauare metre. A . microcosmi (Fig. Paired

, I ” & .

pig, IF); subdi”ided by pulsating expansions of dorsal blood vessel (Fig. 1F). Oval coelomocytes about the size of epidermal sacs (Fig. 1D). Their exterior is finely granulated, with irregular inner structures; some with only one thread-like structure, others with many appear to be attached to the body-wall or to epidermal sacs.

Nephridia of usual type of the genus ( ~ i ~ . 1 ~ ) : antesep- talpart of considerable size, about the Same dorso-ventral diameter than the postseptale, the nephrostome simple and displaced ventrally, the postseptale with a slight constriction at the septum and tapers gradually into a terminal efferent duct. Only two pairs present in the

sp:n.is dominant at t i e type Gcality comprising about 25 % of the total population.

~ ~ h ~ ~ t ~ sp.n. ( ~ i ~ . 2)

Type material. 1 holotype (ZMUM 01 13526) from a city area of Berlin, district of Zehlendorf, green area at the Teltow-channel between Goerzallee and Promenade. From parabrown soil, pH 6.6-7.0 (CaCI,). Collected, in March 1988, with soil corer (diameter 5.6 cm) and extracted with water extraction according to O’Connor (1955), modified after Heitkamp 8~ Schauermann (1982) and Graefe (1984). 9 paratypes (ZMUM 01 13527).

Etymology. The name refers to the sites where the species was found: urban green areas in Berlin.

preclitellar region (on 7/8 and 8/9); postclitellar not in all segments (e.g. in 9 out of 28 postclitellar segments) and with a more elongate form. Dorsal vessel originates in VI, with pulsating expansions in V and VI (Fig. 1F). Penial bulb large, compact, surrounded by a ring of large, oval epidermal cells of unknown function (Fig. 1H). Paired seminal vesicles are of variable size, but usually extending from 10/11 through XI into XII; occasionally further back into XI11 (Fig. 1A). Sperm funnel about 5-6 times longer than wide, length about 1.5 times diameter of worm; the collar part curved in relation to the main axis (Fig. 1C). Sperm duct very long, in a more or less distinct spiral. The ectal duct of the spermatheca is tripartite: beginning with a short stout part, followed by a large expansion in V, which ends in a thin duct of varying length: from equal to the ectal part to 5 times as long extending to VIII. Ampulla very large (nearly the same diameter as the worm), extending to VIII or XI (Fig. 1A); exterior smooth, colour brownish due to the sperm content. The size of the ampulla and its sperm content is probably correlated with the age of the worm.

Remarks

Achaeta microcosmi sp.n. differs from other species of the genus by having a large seminal funnel with an unusually high length/width ratio of about 6 : l and by the large ampulla of the spermatheca, which extends back until the clitellar region. Only three other species, A . bohemica (Vejdovski, 1879) sensu Nielsen & Christensen, 1959, A . vesiculata Nielsen & Christensen, 1959 and A. nielseni Prabhoo, 1960 have only dorsal epidermal sacs. Besides the differences mentioned above, A. microcosmi differs from A . bohemica and A . nielseni by having dorso-lateral oesophageal appendages in V and seminal vesicles, from A. vesiculata by having three pairs of septal glands and from A . nielseni by having a spermatheca extending as far back as IX. Additionally A. microcosmi has fewer seg- ments than the two former species, but this character depends on ecological conditions (Trappmann 1954;

Description

Small to medium-sized species, about 9 mm long with a diameter of 0.22-0.27 mm, about 3 6 4 0 segments. Body brownish in the clitellar region, due to abundant sperm on sperm funnels and in seminal vesicles. No distinct cu- taneous glands.

Setae absent; dorsal (-50 pm) and ventral (=2040 pm) epidermal sacs present (Fig. 2A). Clitellum extend- ing over XII-1/2 XIII; as in the other species of the genus it is covered by regular transverse rows of granulated gland cells (about 20), missing dorsally and mid-ventrally; additionally hyaline gland cells form dorso-lateral longi- tudinal rows usually the same size as granulated clitellar cells (Fig. 2G). Three pairs of septal glands; first pair broadly united dorsally; posterior pairs with narrow dor- sal connections; all three pairs with ventral lobes but without postseptal lobes (Fig. 2A). Chloragogen cells from IV, dense from VII (Fig. 2A). Unpaired dorso- lateral oesophageal appendages in V; 1/5 the diameter of the worm; connected to pharynx by a narrow canal; pulsating expansions of dorsal vessel posterior to append- ages (Fig. 2F). Coelomocytes with a diameter of 20-25 pm, about the size of ventral epidermal sacs; oval or drop- shaded, without a broad hyaline border, with a low number of very short threads at narrow end, exterior granulated (Fig. 2D).

Nephridia of the usual type of the genus: anteseptal part of considerable size, about the same dorso-ventral diameter than the postseptale, the nephrostome simple and displaced ventrally, the postseptale with a slight constriction at the septum and tapers gradually into a terminal efferent duct (Fig. 2E). Only two pairs present in the preclitellar region (on 7/8 and 8/9); postclitellar not in all segments and with a more longish form. Dorsal vessel originating in VII, with pulsating expansions in VI and VII (Fig. 2F). Penial bulb of medium size and compact; male pore surrounded by a longitudinal row of epidermal cells of unknown function (Fig. 2H). Paired seminal vesicles large, usually extending from 10/11 through XI

Zoologica Scripta 20

218 M . Heck and J . Rombke

A

I dbv c'c 0s es

a b

Fig. 2. Achaeta urbana sp.n.-A. Anterior part of the body and main characters.-B. Spcrmatheca (ectal part) with sperm.-C. Sperm funnel.-D. Coelomocyte (a: total view, b: lateral view).-E. Ncphridium (preclitellar).-F. Segments 111-V1.-G. (i) Clitellum (dorsal view) with granulated cells, and (ii) hyaline interspaces.-H. Penial bulbus (a: ventral view, b: lateral view).

Zoologica Scripta 20

Two new species of Achaeta f r o m Germany 219

into XI1 (occasionally further backwards into XIII) (Fig. 2A). Sperm funnel about 5-6 times longer than wide (0.4 mm to 60-80 pm), length about 2 times longer than body diameter (Fig. 2C); collar curved in relation to the main axis, turned over, with a tongue-shaped extension (length about 70pm); sperm duct in a more or less distinct spiral. Ectal duct of the spermatheca beginning with a thick part, sitting perpendicular to body wall without a visible inner canal, but with two rows of big cells (length about 170pm) in it; followed by a spindle-shaped chamber containing spermatophores which is arranged parallel to the body wall and which passes over to a very long duct, opening to a large ampulla (Fig. 2B) with a rugose exterior; ampulla extending to XII, usually only to IX or X.

Remarks

Achaeta urbana sp.n. differs from other species in the genus mainly by the same characteristics as A. micro- cosmi sp.n., i.e. the size of the ampulla of the spermath- eca, extending further back than in most other species of Achaeta (exceptions: A. iridescens, A . neotropica and A . littoralis, which are quite different in other character- istics) and the large sperm funnel with its unusual shape. A. urbana has both dorsal and ventral epidermal sacs and is thus comparable to nine other species of Achaeta. In addition to the two differences mentioned above, A . urbana differs from A. eiseni (Vejdovski, 1877) and A. ufinis Nielsen & Christensen, 1959 by having seminal vesicles, from A. parva Nielsen & Christensen, 1961 and A. aberrans Nielsen & Christensen, 1961, which has also lateral epidermal sacs, by its size (it is at least two times larger) and, together with A. seminalis Kasprzak, 1972, by having the beginning of the dorsal blood vessel in VII (not in VI), and from A. danica Nielsen & Christensen, 1959 by having three pairs of massive septa1 glands. No additional differences to A. bulbosa Nielsen & Christen- sen, 1961 (other than the absolute size of the seminal vesicles) can be given until new specimens of this species have been studied. The closest relationships, despite the differences listed above, seem to be to A. seminalis, A . danica and A. bulbosa which also show a high length/ width ratio of the sperm funnel (about 5: l ) and, excepting A . seminalis, an elongate ampulla extending to X. A . ckristenseni Prabhoo, 1966, found in Kerala (India), has dorsal and ventral epidermal sacs and large ampullae and sperm funnels like A. urbana. However, the spermatheca extends only to VIII, the sperm funnel shows just a length/width ratio of 2.5:1 and the collar is not curved.

Ecology. The species was found in Berlin only at the type locality and other green areas with parabrown soils. Other species at the type locality are: Buchholzia appendiculata, Enchytraeus minutus, Fridericia hege- mon, Henlea ventriculosa, Marionina communis and other species of the genera Enchytraeus, Enchytronia, and Fridericia. Achaeta urbana attained there a mean density of only 3000 Ind./m’ for a total density of enchytraeids of 40,000 Ind./m*. Most individuals were found in the mineral soil (depth 2.5-7.5 em).

Discussion

These two new species of the genus Achaeta are closely related (Table I). Both show the same form and length/

Table I . Main features of A. microcosmi sp.n. and A. urbana sp.n.

Character A. microcosmi A . urbana

Length in rnm Number of segments Epidermal sacs Origin of dorsal vessel Dorsolateral

Septa1 glands appendages

Sperrnatheca extending Sperm funnel ratio Seminal vesicle

=8 35-45 dorsal v 1 V

3 pairs united dorsally

VIII-XI 5 4 : l +

=9 36-40 dorsal + ventral VII V

3 pairs; 1 broadly united dorsally, the others only slightly

IX-XI1 5 6 : l +

width ratio of the seminal funnel and the same general shape of the spermathecal system. They are distinguish- able by distributions of epidermal sacs: only dorsal (A. microcosmi) or dorsal and ventral (A. urbana). Also the origin of the dorsal blood vessel is different.

The two species are distinguishable from all species of Achaeta described in Europe so far (13 according to Kasprzak (1986)), from India (5) (Prabhoo 1966; Dash & Thambi 1978), New Zealand (1) (Benham 1903), North America (1) (Nurminen 1973) and South America (3) (Christoffersen 1979). Two further species, A. vejdovskyi Bretscher, 1902 and A. incisa Friend, 1912 were con- sidered dubious by Cernosvitov (1937). There has so far been no attempt to divide the genus Achaeta, mainly because the phylogeny of the taxon is unknown.

Acknowledgements

We wish to thank Dr K. Coates (Royal Ontario Museum, Toronto, Canada) for her valuable help during the preparation of this manuscript. The work was funded partly by the German Environmental Protection Agency.

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