Zoologica Scripta, Vol. 13, No. 4, pp. 273-275, 1984 Printed in Great Britain

030(2-3256/85 $03.00+ .OO Pergamon Press Ltd.

0 1985 The Norwegian Academy of Science and Letters

Olavius cornuatus sp.n. (Oligochaeta, Tubificidae) from Georges Bank (NW Atlantic)

DALE DAVIS

Battelle New England Marine Research Laboratory, Duxbury, Massachusetts, U.S .A

Accepted 11 July 1984

Davis, D . 1984. Olavius cornuatus sp.n. (Oligochaeta, Tubificidae) from Georges Bank (NW Atlantic).-Zool. Scr. 13: 273-275.

Olavius cornuatm sp.n. is described from Georges Bank off Massachusetts. It is distinguished from other species of Olavius Erseus, 1984 by its curved, horn-shaped atria ending in large. protrusible penes and up to six ectally hooked penial setae per bundle.

Dale Davis, Department of Zoology, University of Hawaii a( Manoa, Edmondson Hall, 2538 The Mall, Honolulu, Hawaii 96822. U.S.A.

Introduction

The genus Olavius was recently established (Erseus 1984) as a result of a much needed revision of the gutless forms of the subfamily Phallodrilinae. The new species de- scribed here brings the total number of species in the genus Olavius to 19.

0. cornuatus sp.n. was found in samples taken from the Georges Bank Benthic Infauna Monitoring Program performed by Battelle New England Marine Research Laboratory for the Minerals Management Service, U.S. Department of the Interior. Very few specimens of the new species were found during the three year study and then only at a few of the sample sites; many times the same sample sites where 0. tenuissimus (Erseus, 1979) was found.

The samples from Georges Bank contained a large diversity of oligochaetes, which have all been treated in other publications. A majority of the species encountered were members of the genera Adelodrilus or Phallodrilus and were treated in publications dealing with their respec- tive genus (Adelodrilus, ErsCus & Davis in press; Phallo- drilus, Erseus in press). The remainder of the species from Georges Bank were treated in a single publication by Davis (in press).

Materials and methods Samples were taken with a van Veen grab and subsequently sieved through a 300 p m screen and fixed in 10% buffered formalin. Samples were later transferred to isopropanol for processing and storage. Oligochaete specimens were stained in Harris haematoxylin or para- carmine and mounted in permanent mounting media on glass slides. The type series are deposited at the United States National Museum of Natural History (USNM), Washington. D.C.

Systematic description

Olavius cornuatus sp.n.

Holotype. USNM 97242.

Type locality. Georges Bank, S E of Massachusetts, U.S.A. , 40O22.2' N, 68" 30.2' W, 103 m, medium to coarse sand (Nov. 1983).

Parutypes. USNM 97243-97246. Three specimens from off Massa- chusetts(Ge0rgesBank): onefrom4O042.0'N,68"3S.3' W , 58m, fineto medium sand (Feb. 1984); one from 4Oo34.2'N. 67" 12.3'W, 138 m, medium to coarse sand (Nov. 1983); one from 40"34.3'N, 67"45.3'W, 98 m, fine to medium sand (Feb. 1984).

Other material examined. Five specimens from off Massachusetts (Georges Bank): one from type locality (collected Feb. 1984); two from 40"42.0'N, 68"35.3'W, 58 m, fine to medium sand (Nov. 1983); two from 40"34.2'N, 67"12.3'W, 138 m, medium to coarse sand (Nov. 1983).

Etymology. The name cornuafus is Latin for "horn-shaped", referring to the shape of the atria of this species.

Description. Length 5.3-5.8 mm, 41-54 segments; diame- ter: 44-119 p m anteriorly, 84-134 pm at segment XI, 44-1 17 p m posteriorly. Clitellum extending over 1/2X- 1/2XII. Secondary annulation strong, particularly post- erior of clitellum; 6-8 annuli per segment. Prostomium conical and pointed, slightly longer than wide. Somatic setae (Fig. 1A) similar in shape throughout; bifid, sig- moid, upper tooth slightly smaller than lower tooth; fine ligament connecting tip of lower tooth with setal shaft; 3 2 4 7 p m long, 1.5-1.8 pm thick, 2 4 per bundle anteriorly; 32-38 p m long, 1.5-1.8 pm thick, (1)-2-(3) per bundle posteriorly. Ventral setae of XI modified into penial bundles (Figs. lB , 2, p s ) ; each consisting of 3-6 slightly sigmoid, ectally hooked setae; 41-56 pm long, 1.5-2.3 p m thick. Penial setae situated obliquely to long axis of worm, slightly posterior to male pores.

Mouth and alimentary canal absent. Chloragogen cells developed along nerve cord and main blood vessels. Male genitalia (Figs. IB, 2) paired in XI. Vas deferens (Figs. 1B, 2, vd) moderately thick-walled and narrow, ciliated; 140-160 pm long, 4-7 pm wide; entering atrium entally. Atrium (Figs. lB , 2, a) small and sharply curved; horn- shaped; narrow entally, widening gradually to ectal end; 40-65 p m long, 8-10 pm wide entally, 18-20 pm wide ectally ; outer lining thin entally, thicker ectally; thick granulated and ciliated inner epithelium; opening into large, delicate, thin-walled penis. Penis (Fig. lB, p ) situated within deep, simple copulatory sac (Fig. lB , cs) when retracted. Penis and copulatory sac can be fully

Zoologica Scripta 13 273

274 D. Davis

Fig. 1. Olavius cornuatus sp.n.-A. Free hand drawing of somatic seta.-

everted as in Fig. 2. Anterior prostate (Figs. lB, 2, p r l ) large and lobed; situated anterior and dorsal to atrium; attached to ental end of atrium, near entrance of vas deferens. Posterior prostate (Figs. lB , 2, pr2) smaller than anterior prostate; lobed; situated posterior to atrium; attached by short stalk to ectal part of atrium. Male pores paired, located in line with ventral setae in posterior part of XI. Spermathecae (Fig. 3) with short

B. Lateral view of male genitalia in segment XI (with penis retracted)

ducts, nearly as wide as long, 14-18 pm long, 15-17 p m wide; elongated ampullae, 60-83 p m long, 12-29 p m wide. Sperm in random masses. Spermathecal pores paired, in line with dorsal setae in X near intersegmental furrow IWX.

Remarks. 0. cornuatus sp.n. is closely related to 0. tenuissimus (Erseus, 1979), 0. pellucidus Erseus, 1984,

Fig. 2. Ohvius cornuatus sp.n. Lateral view o f male genitalia in segment XI (with pcnis fully everted).

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Olavius cornuatus sp.n. 275

where true pene are generally thick-walled and rigid. The definition used here for a true penis requires only that the structure be free and pendant within the penis or copu- latory sac and be capable of being fully everted, which the structure of 0. cornuatus complies with.

Habitat. Sublittoral, fine to coarse sand, 58-138 in.

Distribution. East coast o f U.S .A. off Massachusetts (Georges Bank)

Acknowledgements

I am indebted to Dr Christer Erseus for his technical assistance, encour- agement and moral support; to Dr James Blake and Dr Nancy Maciolck- Blake for putting me in a position where I was able to do this work; and to Battelle New England Marine Research Laboratory for financial support. Specimens from Georges Bank were collected as part of the Georges Bank Benthic Infauna Monitoring Program, supported by Contract No. 14-12-0001-2912from the U.S. Departmentofthe Interior, Minerals Management Service, to Battelle New England Marine Research Laboratory.

50 pm I I

Fig. 3. Oluvius cornuarus sp.n. Spermatheca in segment X .

and 0. rnacer Erseus, 1984. These four species are all small and more or less transparent. Using external fea- tures only, 0. cornuatus and 0. tenuissimus are nearly identical and one cannot be distinguished from the other. Internal structures, however, are much different and 0. cornuatus can be distinguished from 0. tenuissirnus by the curved atria, multiple penial setae, simple copulatory sac and the dorsal and anterior position of the spermathecal pores of the new species.

0. cornuatus is probably most closely related to 0. pellucidus, as both of these species have multiple penial setae and dorsal spermathecal pores. 0. pellucidus is also equipped with a large papilla at the inner end of the copulatory sacs, which may be homologous to the penis of 0. cornuatus.

Abbreviations used in the figures

a atrium cs copulatorysac p penis p r l anterior prostate pr2 posterior prostate p s penial setae vd vasdeferens

References

Baker, H . R. & Erseus, C. 1979. Peosldrilus hrprostatus n.g., n.sp., a marine tubificid (Oligochaeta) from the eastern United States.- Proc. b i d . Soc. Wash. 92: 505-509.

Davis, D. in press. The Oligochaeta of Georges Bank (NW Atlantic), with descriptions of four new species.-Proc. h i d Soc. Wash.

Erseus, C. 1979. Taxonomic revision of the marine genus Phallodrilus Pierantoni (Oligochaeta, Tubificidae), with descriptions of thirteen new species.-Zool. Scr. 8: 1877208.

Erseus, C. 1984. Taxonomy and phylogeny o f the gutless Phallodrilinae (Oligochaeta, Tuhificidae) with descriptlons of one new genus and twenty-two species.-Zool. Scr. 13: 239-272.

Erseus, C. in press. Taxonomy of some species o f Phallodrilus (Oligochaeta, Tubificidae) from the Northwest Atlantic. with

The penes of 0. cornuatus are very different from those Of other Species [e.g., Phaffodrilus biprostatus (Baker &L

Erseus, 1979)] in that they are very thin and delicate,

description of four new species.-Proc. h i d . Soc. Wash. Erseus, C. & Davis, D. in press. Three new species of Addodrilus

(Oligochaeta, Tubificidae) from Georges Bank (NW Atlantic).- f roc. hiol. SOC. Wash.

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