Bryodrilus hallasanensis Dózsa-Farkas, Felföldi, Nagy, and Hong 2018
- Dataset
- New enchytraeid species from Mount Hallasan (Jeju Island, Korea) (Enchytraeidae, Oligochaeta)
- Rank
- SPECIES
- Published in
- Dózsa-Farkas, Klára, Felföldi, Tamás, Nagy, Hajnalka, Hong, Yong (2018): New enchytraeid species from Mount Hallasan (Jeju Island, Korea) (Enchytraeidae, Oligochaeta). Zootaxa 4496 (1): 337-381, DOI: 10.11646/zootaxa.4496.1.27
Classification
- kingdom
- Animalia
- phylum
- Annelida
- class
- Clitellata
- order
- Haplotaxida
- family
- Enchytraeidae
- genus
- Bryodrilus
- species
- Bryodrilus hallasanensis
description
Description. Small lively worm. Holotype 5.2 mm long, 240 µm wide at VIII and 250 µm at clitellum (fixed), 35 segments. Length of paratypes 5 – 8 mm, width 200 – 260 µm at VIII and 2 40 – 330 µm at clitellum in vivo, length of fixed specimens 2.9 – 5.2 mm, width 170 – 220 µm at VIII and 210 – 250 µm at clitellum, segments (24) 30 – 40. Chaetae slightly sigmoid, without nodulus. Chaetae in a bundle arranged in asymmetric fan of unequal size, those towards dorsal and ventral midlines of body gradually smaller; largest ventral chaetae in a bundle preclitellarly 33 – 37 µm, the next in line 34 – 30 µm, 29 – 25, and 28 – 23 µm long and 1.8 – 2 µm wide. In terminal segments the largest chaetae slightly longer, 40 – 45 µm. Chaetal formula 2,3,4 – 3: 3,4, (5) – 4,3 (2). Chaetae absent at XII. In ventral preclitellar bundles usually 4 chaetae, 5 in some bundles in some specimens from site 4. Epidermal gland cells conspicuous preclitellarly, 5 – 6 rows per segments (Fig. 6 A). Head pore at 0 / I, a longitudinal slit. Body wall 20 – 30 µm thick, cuticle thin about 1 µm, longitudinal muscle layer well-developed. Clitellum from XII – 1 / 2 XIII, hyalocytes and granulocytes in rows dorsally, hyalocytes larger than granulocytes, the latter often triangle-shaped (Fig. 6 B), absent ventrally (about 70 µm distance) (Fig. 7 G). Brain 95 – 110 µm long and 1.7 – 2.2 times longer than wide (fixed and in vivo), anteriorly slightly convex, posteriorly rounded (Fig. 6 C – D). Pharyngeal glands 3 pairs in IV – VI, mostly all free dorsally with ventral lobes (Fig. 6 H), sometimes first pair connected dorsally. Oesophageal appendages (Figs. 6 H, 7 A – B) in VI, two pairs of irregularly lobed bodies (about 30 – 50 µm long) attached to oesophagus ventro-laterally with small canals (these canals collapse under longer examination in vivo and give a homogeneous aspect of the structure). Intestine widening abruptly in VII and VIII (Fig. 6 E). Four pairs of preclitellar nephridia from 6 / 7 to 9 / 10; anteseptale consisting of funnel only, medial rise of efferent duct (Figs. 6 F, G). Coelomocytes nucleate, oval or discoid, about 15 – 26 µm long in vivo (13 – 17 µm, fixed), finely granulated (Fig. 7 C, D). Dorsal blood vessel from XIII, blood colourless. Anterior bifurcation in peristomium (Fig. 6 C). Pars tumida of midgut XX – XXVI, occupying 2 – 3 segments. Chloragocytes from VI, about 12 – 18 µm large. Seminal vesicle small in XI. Sperm funnels (Fig. 7 E, F) pear-shaped, 70 – 120 µm long and 2 – 3 times longer than wide in vivo (60 – 95 µm long and 1.5 – 2 times longer than wide in fixed specimens). The collars well developed, as wide as funnel body or narrower. Diameter of sperm ducts 6 – 8 µm. Spermatozoa 70 – 85 µm long, heads 22 – 30 µm in vivo. Male glandular bulb spherical, diameter about 60 – 80 µm in vivo (40 – 70 µm, fixed) (Fig. 7 G, I). Bursal slits longitudinal, bent laterally. Subneural glands absent. Spermathecal ectal ducts about 60 – 90 µm long and 13 – 18 µm wide in vivo (50 – 80 µm long and 12 – 14 µm wide, fixed), no ectal glands, the ampullae lemon-shaped, diameter 20 – 30 µm in vivo and 22 – 25 µm, fixed. The ental ducts merging entally and with joint opening into oesophagus in VI (Figs. 5 F, 7 J). 1 – 3 mature egg at a time.
diagnosis
Diagnosis. The new species can be recognized by the following combination of characters: (1) small size (5 – 8 mm in vivo), segments 30 – 40; (2) chaetae maximum 4 – 5 per bundle, slightly sigmoid without nodulus; (3) conspicuous epidermal gland in 5 – 6 rows; (4) four pairs of preclitellar nephridia; (5) coelomocytes oval or discoid with fine granules; (6) pharyngeal glands free dorsally and with ventral lobes; (7) two pairs of irregularly lobed oesophageal appendages in VI, with small canals; (8) sperm funnels pear-shaped, 70 – 120 µm long and 2 – 3 times longer than wide; (9) seminal vesicle small; (10) male copulatory organs spherical, diameter about 60 – 80 µm; (11) spermathecae communicating with oesophagus, ectal ducts 60 – 90 µm long and 13 – 18 µm wide, the ampullae lemon-shaped, diameter 20 – 30 µm, ectal gland absent.
diagnosis
Differential diagnosis. Among the previously described Bryodrilus species, four species have fewer than 40 segments and 7 mm length in vivo: B. librus (Nielsen & Christensen, 1959), B. diverticulatus Černosvitov, 1929, B. tunicatus Dózsa-Farkas & Christensen, 2002, B. archipelagicus Christensen & Dózsa-Farkas, 2006, but clearly separate from this species in the following main characters: B. librus has 5 pairs of preclitellar nephridia, the oesophageal appendages are rounded, well visible and the midgut pars tumida can be found more forward (in XVII – XX), while the new species has only 4 pairs of preclitellar nephridia, the oesophageal appendages are lobed, not easily seen and the midgut pars tumida occupies 2 – 3 segments (in segments XX – XXVI). B. diverticulatus differs by 5 pairs preclitellar nephridia and hollow and pulsating oesophageal appendages. B. tunicatus has larger sperm funnels (200 – 300 µm long 4 – 5 times longer than wide vs. 70 – 120 µm and 2 – 3 times longer than wide, in the new species) and spermathecae with sessile diverticula in which the spermatozoa are arranged in smaller bundles. The spermathecae of B. archipelagicus are more conspicuous: the ectal duct is 220 µm long and approximately 30 µm wide and the diameter of ampullae is 90 – 95 µm (the ducts has a size of 60 – 90 to 13 – 18 µm and the ampullae 20 – 30 µm in B. hallasanensis sp. n.).
distribution
Distribution and habitat. In Korea, Mt. Hallasan, sites 2, 4 – 6, 8, 11, 12. Dominant at sites 4, 5.
etymology
Etymology. Named after the mountain where it was found.
materials_examined
Type material. Holotype: NIBRIV 0000810590, slide No. 2199, adult, stained whole mounted specimen. Type locality: Mt. Hallasan in Gwaneumsa trail, Jeju Island, Korea, soil and litter layers of Sorbus commixta tree, N 33 ˚ 22 ' 06.8 ", E 126 ˚ 32 ' 02.2 ", 1694 m asl, 0 9.06.2016, leg. Y. Hong. Paratypes (in total 18 stained, adult specimens on slides and 47 specimens in 70 % ethanol): NIBRIV 0000810591, slide No. 2177, from type locality, NIBRIV 0000811382, slide No. 2377, site 4, P. 115.1.1 - 115.1.6, slides No. 2174 - 2175, 2178, 2200 - 2202, from type locality, P. 115.2.1 - 115.2.8 slides No. 2181 - 2183, 2258, 2373 - 2376, site 4, P. 115.3, slide No. 2327, site 2, P. 115.4, slide No. 2328, site 8. In 70 % ethanol: P 115.5, from type locality, three species P. 115.6, site 2 one specimen; P. 115.7, site 4 35 specimens; P. 115.8, site 6 one specimen; P. 115.9, site 11 six specimens; P. 115.10, site 12 one specimen. Further material examined. 16 specimens investigated in vivo, 4 of them processed for DNA analysis.