Decimodrilus, Dózsa-Farkas & Nagy & Felföldi & Hong, 2019

Dózsa-Farkas, Klára, Nagy, Hajnalka, Felföldi, Tamás & Hong, Yong, 2019, Decimodrilus, a new enchytraeid genus from Korea (Annelida, Clitellata, Enchytraeidae), Zootaxa 4661 (2), pp. 385-399 : 390-395

publication ID	https://doi.org/ 10.11646/zootaxa.4661.2.7
publication LSID	lsid:zoobank.org:pub:F13C5EB5-6BDF-43CB-A4E0-598572DDDBA6
persistent identifier	https://treatment.plazi.org/id/F31B87C6-FFCA-8B11-4DD0-FF36FF0253C0
treatment provided by	Plazi
scientific name	Decimodrilus
status	gen. nov.

Treatment

Decimodrilus View in CoL g lobulatus sp. n.

( Figs 1 View FIGURE 1 C–D, 4–5, 6F, D, G–H)

Holotype. NIBRIV0000843111, slide No. 2519 adult, stained whole mounted specimen.

Type locality. Soil of Quercus mongolica forest, Mt. Gyebangsan, Nodong-ri, Yongpyeong-myeon, Pyeongchang-gun, Gangwon-do, South Korea (N 37°42’27.9”, E 128°29’02.3”), 848 m asl.

Paratypes. In total 9 specimens, same data as for holotype. NIBRIV0000843112, slide No. 2551, NI- BRIV0000843113 , slide No. 2533, + P.123.1–P123.7 No. 2534, 2504, 2520, 2526, 2553, 2559, 2560. (No. 2533 = DNA 1224, No. 2534 = DNA 1215) .

Further material examined. Two subadult specimens.

Etymology. Named after the sperm-rolls (globulus) in the spermathecal ampulla, globulatus (Latin) = globulecarrier.

Diagnosis. (1) Small size (6.5–8.3 mm, in vivo), segments 31–33; (2) chaetae maximum 5 per bundle, straight or slightly bent in a bundle arranged in asymmetric fan without nodulus; (3) five pairs of nephridia preclitellarly, anteseptale consisting of funnel only; (4) the dorsal lobes of pharyngeal glands in IV connected dorsally, pairs in V connected or not, the third pair free, all with ventral lobes, one pair secondary glands in VI; (5) dorsal blood vessel origin in XII, blood colorless; (6) intestinal diverticulum in IX–X; (7) sperm funnel cylindrical 70–130 μm long, 1.7–3.5 times longer than wide (in vivo); (8) seminal vesicle absent; (9) spermatheca has a 110–150 μm long and 14–22 μm wide ectal duct with two ectal glands and a thin-walled ampulla; in ampulla, the sperm forms 2–3 sperm rolls; ental duct fused proximally and connect jointly with the oesophagus; (10) mostly 2 mature eggs at a time.

Description. Small enchytraeid worm. Holotype 4.15 mm long, 240 µm wide at VIII and 280 µm at clitellum (fixed), 32 segments. Length of paratypes 6.5–8.3 mm, width 210–300 µm at VIII and 260–360 µm at clitellum in vivo, length of fixed specimens 3.6–6.0 mm, width 200–280 µm at VIII and 230–320 µm at clitellum, segments 31–33. Chaetal formula 3,4–4,3,2: 3,4,5,(6)–4,3,2. Chaetae straight or slightly bent without nodulus, in a bundle arranged in asymmetric fan, those towards dorsal and ventral midlines of body gradually smaller ( Fig. 4D View FIGURE 4 ), e.g. 42, 40, 32, 31 µm long in ventral bundle of IX. Maximum length 36–42 µm in preclitellar region and posterior segments alike, width about 2.5–3 µm; chaetae absent in XII. Epidermal glands in 5–6 transverse rows ( Fig. 4C View FIGURE 4 ). Body wall 15–25 μm thick, cuticle less than 1 μm. Clitellum extending over XII– ½ XIII, girdle-shaped, gland cells irregularly scattered; larger hyaline gland cells are surrounded by smaller granular gland cells ( Figs 4 View FIGURE 4 I–J), absent midventrally between the bursal slits and before them, with about 60–85 µm distance, posteriorly the structure same kind as dorsally ( Fig. 4K View FIGURE 4 ). Head pore 0/I, longitudinal slit ( Fig. 4E View FIGURE 4 ).

Brain ( Figs 4 View FIGURE 4 A–B) about 110–130 μm long in vivo and 96–120 μm fixed, 1.5–2 times longer than wide, anteri- orly slightly concave, posteriorly truncated. Oesophageal appendages absent. Postpharyngeal bulbs well developed ( Fig. 4G View FIGURE 4 ). Pharyngeal glands united in IV and V dorsally, but sometimes only touching each other, the third pair free, all with ventral lobes, and one small pair of secondary glands in VI ( Fig. 5A View FIGURE 5 ). Intestinal diverticula in IX–3 / 4X, less developed than in D. diverticulatus sp. n. ( Figs 5 View FIGURE 5 E–H), 100–160 μm wide in vivo (110–160 μm when fixed) about 30–50 μm wider than wide the intestine before and after the diverticula. Chloragocytes about 15–25 μm high. Dorsal blood vessel from XII, blood colorless; the anterior bifurcation in peristomium. Five pairs of preclitellar nephridia from 6/7 to 10/11; anteseptale consisting of funnel only, efferent duct arises mid-ventrally ( Figs 1C View FIGURE 1 , 4H View FIGURE 4 ). Coelomocytes ( Figs 5 View FIGURE 5 B–C) oval mucocytes, granulated, about 24–40 μm long in vivo and 20–38 μm, when fixed. Midgut pars tumida in XVII–XXI occupying 2–3 segments. Seminal vesicle absent. Sperm funnels ( Figs 5 View FIGURE 5 I–J) cylindrical, 70–130 μm long, 1.7–3.5 times longer than wide in vivo, (50–110 μm long and 2–3 times longer than wide, when fixed); the collar narrower than the funnel body; diameter of sperm ducts 5–7 μm. Spermatozoa 80–110 μm long, heads 40–50 μm in vivo (spermathozoa 50–70 μm long, heads 15–22 μm in fixed specimens). Male glandular bulb ( Figs 5 View FIGURE 5 K–L) compact, well developed, about 115–140 μm long, 50–80 μm wide and 40–50 μm high in vivo (50–90 μm long, 40–90 μm wide, 50–60 μm high, fixed). Spermathecae ( Figs 1D View FIGURE 1 , 6B, D View FIGURE 6 , G–H) attached to the oesophagus; ectal ducts 110–150 μm long and 14–22 μm wide in vivo (70–120 μm long and 15–18 μm wide, fixed), canal at orifice 3 μm wide, distally widening slightly at ampulla 5–8 μm wide in vivo with one or two 24–55 μm long stalked ectal glands. Ampullae thin-walled and onion-shaped, diameter 25–36 μm (22–32 μm, fixed), sperm arranged in 1–3 regular sperm rolls ( Figs 6D View FIGURE 6 , G–H). Ampullae united proximally, ental duct about 25–50 μm long in vivo (20–25 μm fixed) and connects jointly with the oesophagus, the common duct 25–40 μm long. 2–3 mature eggs at a time.

Distribution and habitat. Only known from type locality in South Korea, at site 2: Mt. Gyebangsan, Nodongri, Yongpyeong-myeon, Pyeongchang-gun, Gangwon-do (N 37°42’27.9”, E 128°29’02.3”), 848 m asl.

Differential diagnosis. D. globulatus sp. n. similar to D. diverticulatus sp. n. in many traits, but slightly larger [6.5–8.3 m long vs. 4.6–6.9 mm long in vivo and 3.6–6.0 mm long vs. 3.1–4.3. mm respectively, when fixed)]. Other principal differences between D. diverticulatus sp. n. and D. globulatus sp. n. are as follows (character states of D. diverticulatus mentioned first): clitellum saddle shaped ( Fig. 2G View FIGURE 2 ) (vs. girdle shaped in posterior half, absent ventrally only between the bursal slits and before them) ( Fig. 4K View FIGURE 4 ); the spermathecal ampullae wider, with two diverticula-like protrusions, sperm-rolls absent, only 2–3 round sperm masses in them (vs. diverticula absent, sperm rolls in onion-shaped ampulla); the male copulatory organs smaller, 80–90 μm long (vs. 115–140 μm) in vivo, and the maximum number of chaetae in a bundle is four (only in the case of one specimen five) vs. often five (in one specimen 6 in a single bundle); moreover, the intestinal diverticula in IX–X are weakly developed in D. globulatus sp. n.