PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 128(1):80–85. 2015. Mesenchytraeus asymmetriauritus, a new enchytraeid (Annelida, ) from northeastern China

Jing Chen and Zhicai Xie* (JC) College of Life and Science, Zao Zhuang University, Zaozhuang, Shandong Province, China; (ZX) The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences,Wuhan, Hubei Province, China, e-mail: [email protected]

Abstract.—A new enchytraeid , Mesenchytraeus asymmetriauritus sp. nov., collected from terrestrial habitats of Changbai Mountain in the northeast China, is described. It is characterized by the dorsal vessel originating in XV–XVII, four pairs of preclitellar nephridia in 6/7–9/10, spermathecae attached to oesophagus in segment V and each possessing three or four ear-shaped diverticula of different size, one pair of asymmetrical sperm sacs occupying X–XVII and containing bulk of naked sperm bundles, atrium cylindrical with 4 prostate-like glands and distinct from vas deferens, and well-developed egg sac extending to XVI–XVII.

Keywords: China, Clitellata, , Mesenchytraeus, new species

Mesenchytraeus Eisen, 1878 is one of the Materials and Methods most speciose genera in the Enchytraeidae, containing as many as 85 species and Worms were collected from the field subspecies worldwide (Cech et al. 2012, during Mar 2014 by taking soil samples Christensen & Do´zsa-Farkas 2012, and extracting them in the laboratory, Schmelz & Collado 2012, Shen et al. using a standard hot wet funnel device 2012a). Some taxa can perfer to glacial (O’Connor 1962, Healy & Rota 1992). All waters or tundra, but most of them occur mature worms were examined with a in cold permanently humid habitats rich in stereomicroscope and measured micro- organic matter (Welch 1919, Christensen scopically while alive. Live observations &Do´zsa-Farkas 1999, Rota & Brinkhurst included general dimensions and body 2000). color. All other characters were studied Changbaishan Mountain, located in with a light microscope equipped with Jilin Province, northeast China, is rich in interference contrast optics. For the exam- enchytraeid species diversity (Lian et al. ination of the soft–bodied internal organs 2011). During previous investigations, and surface structures, we gently pressed some species new to science and endemic the living specimens between a slide and were found there, including three Mesen- coverslip in a drop of tap water. Subse- chytraeus (Shen et al. 2011, 2012a, b). quently, worms were preserved in 10% During a further investigation of the formalin or 70% alcohol (for future enchytraeid fauna there, we identified one molecular studies). For taxonomic obser- new species belonging to Mesenchytraeus. vation, some specimens were stained in Herein, the species is described. paracarmine, dehydrated in an alcohol series, and mounted in Canada balsam, * Corresponding author. or dissected. Drawings from whole mounts DOI: 10.2988/0006-324X-128.1.80 were made with the help of an Olympus VOLUME 128, NUMBER 1 81 drawing tube. The type material of the new Head pore near the tip of prostomium, as species are deposited in the Museum of a longitudinal slit. Epidermal gland cells Aquatic Organisms (MAO), Institute of inconspicuous, almost absent. Chaetal Hydrobiology, Chinese Academy of Sci- formula: 3, 4–3, 4: 4(3) 4. No enlarged ences, China. chaetae. Chaetae sigmoid and nodulated, Unless otherwise specified, measure- distally thinner and single-pointed. Both ments refer to sexually mature, fixed (both lateral and ventral chaetae shortest in whole-mounted and dissected) specimens. segment II, reaching the maximum length When ‘vivo’ is used, measurements refer to in VII (Fig. 1A–F), and gradually short- living specimens. ening again posteriorly. Ventral chaetae longer and stouter than corresponding lateral ones. Lateral chaetae 46–75 lm Mesenchytraeus asymmetriauritus, new long, 2.1–4 lm thick. Ventral chaetae 60– species 90 lm long, 3.2–5 lm thick. Chaetae of Fig. 1 XII lacking in sexually fully-mature spec- imens. Clitellum elevated inconspicuously, Holotype.—Sexually mature specimen extending from middle of XI to XIII. (JLO201400001) collected in March 2014, Hyalocytes and granulocytes irregularly stained and whole-mounted in Canada arranged in lateral area of XII; glands balsam. scarce in mid-dorsal and mid-ventral of Type locality.—Mixed coniferous and XII. Two separate male pores ventrolater- broadleaved forest, Mt. Changbai, Jilin al in ventral-middle of XII. Paired sper- Province (42.335798N, 127.884468E, 1109 mathecal pores in 4/5, each on the lateral m above sea level), dark brown forest soil line. under roots of Pinus koraiensis and Acer Brain in I–II, trapezoidal, deeply con- ukurunduense, 22–27 March 2014, coll. Z. cave anteriorly and truncate or weakly J. Piao. incised posteriorly, 130–150 lm long, 40– Paratypes.—Four whole specimens 50 lm wide. Dorsal vessel arising from and one dissected adult specimen XV–XVII. Dorsal vessel bifurcating be- (JLO201400002–201400006), collected neath front of the brain, circumesophageal from the same locality and date as the commissures merging ventrally in IV. holotype. Blood colorless. Two pairs of primary Other material examined.—About 15 pharyngeal glands in 4/5 and 5/6, both additional mature and 10 submature spec- without dorsal connection and attached to imens, all from the type locality, were septa. Three pairs of secondary pharyngeal examined. glands in VI–VIII. Gradual transition Etymology.—‘‘Auritus’’ means ear- between oesophagus and intestine. No equipped, and ‘‘asymmetri-‘‘means imbal- oesophageal appendages. No intestinal anced or unequal. The specific name diverticula. Chloragogen cells brownish, ‘‘asymmetriauritus’’ refers to the sperma- dense, granulated, beginning from V back- thecal ampulla bearing three to four ear- wards. Coelomocytes elliptic, 25–50 by 12– shaped diverticula of different size. 15 lm. Preclitellar nephridia 4 pairs from Description.—Small worms, yellowish in 6/7–9/10. Nephridial anteseptale consisting vivo. Body length 9–12 mm in vivo and of funnel only, postseptale bilobed near 7.6–8.0 mm after fixation (holotype 8.0 septum, with folded canal and scarce mm), body width 0.3–0.4 mm at V, 0.4–0.5 interstitial tissue, efferent duct arising mm at clitellum in vivo (0.22–0.24 mm at V between the two lobes. and 0.27–0.29 mm at XII after fixation). Sperm funnel bell-shaped, with collar Segment number 43–54 (holotype 50). weakly developed, 125–200 lm long, 75– 82 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Fig. 1. Mesenchytraeus asymmetriauritus. A, lateral chaetae in III; B, lateral chaetae in V; C, lateral chaetae in VII; D, ventral chaetae in III; E, ventral chaetae in V; F, ventral chaetae in VII; G, spermatheca; H, sperm funnel; I, male organs in clitellar region. Scale bars: A–F ¼ 10 lm; G–I ¼ 50 lm. Abbreviations: at, atrium; dt, diverticulum; ecd, spermathecal ectal duct; plg, prostate-like glands; sa, spermathecal ampulla; vd, vas deferens.

125 lm in maximum width, backwards irregular spirals in coelom of XII–XIV, tapering into vas deferens. Head of sper- gradually widening posteriorly and enter- matozoa ca. 110–120 lm long (Fig. 1H). ing atrium apically. Atrium slightly wider Vas deferens with conspicuous ciliated than vas deferens, ca. 170–280 lm long canal, ca. 20–25 lm wide, wound in and 28–50 lm wide, with thin muscular VOLUME 128, NUMBER 1 83 layers and thick epithelium extending into such as Acer ukurunduense and Eleuther- penial bulbs medially in XII. No cilia ococcus senticosus are also common. observed in atrial canal. Atrium with four long (200–300 lm) prostate-like glands projecting in opposite directions. Penial Discussion bulbs ventral, compact, consisting of masses of glandular cells and muscle Mesenchytraeus asymmetriauritus is strands. Several small accessory glands characterized by the 1) dorsal vessel extending in different directions around beginning from XV–XVII; 2) four pairs the male pore. Paired sperm sacs of of preclitellar nephridia in 6/7–9/10; 3) one different size, both originating at X and pair of asymmetrical sperm sacs occupying reaching separately and posteriorly into X–XVII, containing bulk of naked sperm XV–XVII, containing numerous naked bundles; 4) each spermatheca endowed but regular sperm bundles. One egg sac with three or four diverticula of different extending into XVII. One to two eggs shapes and sizes and attached entally to mature at a time. oesophagus in segment V; 5) male atrium Paired spermathecae confined to V (Fig. cylindrical, with 4 prostate-like glands and 1G). No ectal glands visible. Ectal duct distinct from vas deferens; and 6) well- stout, thick-walled and rich in muscle developed egg sac extending to XVI–XVII. fibres, ca. 75–100 lm long and 20–40 lm Most of the species in Mesenchytraeus wide, projecting into ampulla. Latter as have one or two spermathecal ampullar diverticula or none. So far, only three long as ectal duct, comprising an elongate congeners have been described with three proximal part and a short and widened or more diverticula, including the ice-worm distal one. Each ampulla possessing 3–4 M. solifugus (Emery, 1898) (possessing 3 asymmetrical diverticula sessile in the diverticula), the Siberian and wetland M. proximal part, both ampullar body and mirabilis Eisen, 1878 (3–5), and the aquatic diverticula filled massively with sperm M. vshivkovae Timm, 1994 (at least 6) bundles in fully mature specimens. One (Welch 1919, Eisen 1905, Cejka 1914, small globular diverticulum, ca. 50–80 lm Goodman 1971, Timm 1994, Christensen in diameter, attached to ampulla ventrally, &Do´zsa-Farkas 1999, Shain et al. 2000). others (2–3) much larger (variable in size All three species differ from M. asymme- between 60–120 lm long and 70–80 lm triauritus by having an intraclitellar origin wide) and ear-shaped, attached dorsally to of dorsal vessel in common (Table 1). ampulla on the opposite sides and some- Furthermore, M. mirabilis is distinguished what ectally. Ental ducts of the sperma- from M. asymmetriauritus by its dark body thecae join separately the ventral side of color, more chaetae per bundle (up to 7), oesophagus in 5/6. the nature of spermathecae (turret-like ones Habitat.—Mesenchytraeus asymme- with up to 5 globular diverticula and free triauritus prefers dark brown forest soil from oesophagus), the shorter and broader that contains a mixed snow-ice water vas deferens and the absence of atrial gland component. The soil water humidity is (Eisen 1905, Christensen & Do´zsa-Farkas ca. 50% and the depth of litter ca. 12 mm. 1999) (Table 1). The stream-dwelling M. The sample locality is ca. 1109 m in vshivkovae differs from M. asymmetriaur- altitude and located in a mixed coniferous itus by the lack of atrial glands, and by broadleaved forest. This region mainly possessing at least 6 ampullar diverticula in contains tall trees such as Pinus koraiensis, each spermatheca (Timm 1994). The ice- Quercus mongolica, Tilia amurensis, Acer worm, M. solifugus, is distinctly separate mono, and Betula platyphylla. Some shrubs from M. asymmetriauritus by its dark 84 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Table 1.—Comparison of Mesenchytraeus asymmetriauritus with three putatively related species.

Species/character M. mirabilis Eisen, 1878 M. vshivkovae Timm, 1994 M. solifugus (Emery, 1898) M. asymmetriauritus

Length/mm 10.0–15.0 5.0–12.5 10.0–15.0 10.0–13.0 Body color blackish brown ? dark brown whitish Segment number 49–64 59–61 50–60 39–54 Chaetal formula 2,3,4–2,3,4:5,6,7–5,6 2,3–3, 4,5: 2,3–4,5 4,5,3–4,5,3:2,3–2,3 3, 4–3, 4: 4(3)–4 Enlarged chaetae absent absent in ventral bundles of absent XI Spermathecae free, 3–5 globular attached to attached to attached to diverticula oesophagus, up to 6 oesophagus, 3 (2) oesophagus, 3(4) diverticula diverticula diverticula Dorsal vessel origin XII/XIII XIII XII XV–XVII Sperm funnel ? cylindrical cylindrical bell–shaped Vas deferens short long long long Sperm sac XIV XX 1, extending to XX 2, X–XVII Egg sac ? XX–XXIII 1, extending to XXII 1, extending to XVI–XVII Atrium no atrial glands no atrial glands 8 atrial glands 4 atrial glands Penial bulb accessory glands 4–5 glands numerous, long many, long many Distribution Mesenkin on the Komarovka Stream Ice worms, western Mt. Changbai, shore of the in the Far East of coastal glaciers of China Yenisey River, and Russia North America Faddeyevsky Island, Siberia, Russia Reference Eisen 1905, Timm 1994 Goodman 1971, This study Christensen & Eisen 1905, Welch Do´zsa-Farkas 1999 1919, Shain et al. 2000 brown body color, obvious copulatory Acknowledgments papillae, the abrupt distal setal curvature We are greatly indebted to Mr. Z. J. and the enlarged ventral chaetae in XI, the Piao of Changbai Mountain Academy of fewer spermathecal diverticula, more atrial Sciences and Mr. Ji Ye of the Institute of glands, and one sperm sac extending to XX Applied Ecology, Chinese Academy of (Eisen 1905, Welch 1919, Goodman 1971, Science, for their help in collecting the Shain et al. 2000). enchytraeid samples and providing the Mt. Changbai harbors a highly diverse useful habitat data. This work was finan- assemblage of enchytraeids, numbering a cially supported by the National Natural total of ca. 50 species so far (Chen 2009, Science Foundation of China (No. Shen 2013), including three species of 31272270, No. 31100388) and the Natural Mesenchytraeus (Shen et al. 2011, 2012a, Science Foundation of Shandong Province b). These taxa had been all collected during (ZR2010CL004, ZR2011CQ012). summer months. M. asymmetriauritus is the first record obtained in the spring season, Literature Cited indicating that this well-preserved moun- Cech, G., G. Boros, & K. Do´zsa-Farkas. 2012. tainous ecosystem may contain an even Revision of Bryodrilus glandulosus (Do´zsa- larger array of enchytraeid species. Farkas, 1990) and Mesenchytraeus kuehnelti VOLUME 128, NUMBER 1 85

Do´zsa-Farkas, 1991 (: Enchytraei- Clitellata) from the temperate rainforest of dae) using morphological and molecular data. British Columbia, Canada, with a revised Zoologischer Anzeiger 251:253–262. diagnosis of the Mesenchytraeus. The Cejka, B. 1914. Die Oligochaeten der Russischen in Journal of Zoology, London 252:27–40. den Jahren 1900–1903 unternommenen Nord- Schmelz, R. M., & R. Collado. 2012. A guide to polarexpedition III. Zapiski Akademii Nauk European terrestrial and freshwater species of 29: l–24. Enchytraeidae (Oligochaeta): First supple- Christensen, B. & K. Do´zsa-Farkas. 1999. The ment. Landbauforschung vTI Agriculture enchytraeid fauna of the Palearctic tundra and Forestry Research, Special Issue 357:53– (Oligochaeta, Enchytraeidae). Biologiske 66. Skrifter 52: 1–37. Shain, D. H., M. R. Carter, K. P. Murray, K. A. Christensen, B. & K. Do´zsa-Farkas. 2012. A new Maleski, N. R. Smith, T. R. McBride, L. A. genus Globulidrilus and three new enchytraeid Michalewicz, & W. M. Saidel. 2000. Morpho- species (Oligochaeta: Enchytraeidae) from logic characterization of the ice worm Mesen- Seoraksan National Park (Korea). Journal chytraeus solifugus. Journal of Morphology of Natural History 46:2769–2785. 246:192–197. Eisen, G. 1905. Enchytraeidae of the West Coast of Shen, Q., J. Chen, & Z. C. Xie. 2011. Mesenchytraeus North America. Harriman Alaska Expedition, megachaetus, a new enchytraeid with enlarged with cooperation of Washington Academy of ventral chaetae (Annelida, Clitellata) from Sciences. Doubleday, Page and Co., New Changbaishan Mountain, China. Proceedings York, 167 pp. of the Biological Society of Washington ` Emery, C. 1898. Sur un oligochete noir des glaciers 124:127–133. de l’Alaska. Revue Suisse de Zoologie 5 Shen, Q., J. Chen, & Z. C. Xie. 2012a. Mesenchy- (Suppl):21–22. traeus monodiverticulus sp. nov (Annelida: Goodman, D. & W. B. Parrish. 1971. Ultrastructure Clitellata: Enchytraeidae) from Changbai of the epidermis in the ice-worm, Mesenchy- Mountain, with a key to Mesenchytraeus with traeus solifugus. Journal of Morphology enlarged chaetae. Proceedings of the Biolog- 135:71–86. ical Society of Washington 125:215–227. Lian, H., J. Chen, J. Xiong, X. M. Jiang, & Z. C. Shen, Q., J. Chen, & Z. C. Xie. 2012b. Mesenchy- Xie. 2011. Structure and distribution of traeus anisodiverticulus, a new enchytraeid enchytraeid communities from Mountain with enlarged ventral chaetae (Annelida, Changbaishan in China, with emphasis on the influence of environmental variables. Clitellata) from north-eastern China. Italian European Journal of Soil Biology 47:223–229. Journal of Zoology 79:86–91. Healy, B., & E. Rota. 1992. Methods for collecting Timm, T. 1994. Propappidae and aquatic Enchy- enchytraeids during expeditions. Soil Biology traeidae Oligochaeta from the farthest south- & Biochemistry 24:1279–1281. east of Russia. Hydrobiologia 278:67–78. O’Connor, F. B. 1962. The extraction of Enchy- Welch, P. S. 1919. Further studies on North traeidae from soil. Pp. 279–285 in P. W. American mesenchytraeids (Oligochaeta). Murphy, ed., Progress in soil zoology. Lon- Transactions of the American Microscopical don: Butterworths. Society 38:175–188. Rota, E., & R. O. Brinkhurst. 2000. Mesenchytraeus antaeus, a new giant enchytraeid (Annelida, Editor: Rick Hochberg.