Polypheretima tabhingensis Lam, Nguyen & Nguyen, 2018

Lam, Dang H., Nguyen, Tung T., Hoang, Sam V. & Nguyen, Anh D., 2018, Two new earthworm species of the genus Polypheretima Michaelsen, 1934 (Clitellata: Megascolecidae) from central Vietnam, Raffles Bulletin of Zoology 66, pp. 572-579 : 575-578

Polypheretima tabhingensis Lam, Nguyen & Nguyen , new species

( Fig. 3 )

Type material. Holotype: 1 mature specimen (CTU-EW.185. h01), natural forests (15°38′01.2″N, 107°43′42.1″E), Ta Bhing Commune, Nam Giang District , Quang Nam Province, 13/3/2017, coll. Lam Hai Dang.

Paratypes: 3 mature specimens (CTU-EW.185.p02), same data as for holotype; 6 mature specimens (CTU-EW.185. p03) regenerated forests (15°38′10.4″N, 107°39′30.5″E), Ta Bhing Commune, Nam Giang District , Quang Nam Province, 25/3/2017, coll. Lam Hai Dang.

Other material. 2 mature specimens (CTU-EW.185.04) same data as for paratype (CTU-EW.185.p03).

Diagnosis. Small sized worm, length 80–85 mm, diameter 3.0– 3.4 mm, 129–145 segments. Prostomium epilobous. First dorsal pore in 12/13. Setal number: 85–89 in viii, 96–101 in xxx, 12–16 between male porophores in xviii. Spermathecal pores lateroventrally paired in intersegmental furrows 6/7/8/9. Genital markings large, paired in 17/18, and xix to xxi, in line with male porophores. Copulatory pouches absent. Holandric.

Description. External characters: Body cylindrical, small size; length 80–85 mm, diameter 3.0– 3.4 mm, weight 0.45–0.53 g, 129–145 segments. Body uniformly whitish grey. Prostomium open epilobous. First dorsal pore in 11/12. Setae perichaetine, short; pre-clitellar setae stouter and sparser than post-clitellar setae; setal number: 85–89 in viii, 96–101 in xxx, 12–16 between male porophores in xviii. Clitellum annular, xiv–xvi, dark brown, smooth, without dorsal pores and setae. Female pore single, mid-ventral in xiv.

Spermathecal pores lateroventrally paired in intersegmental furrows 6/7/8/9. Two pairs of round, small genital markings in ventral presetal ix and x. Male pores simple on conical porophores in xviii, without copulatory pouches; ventral distance between male porophores about 0.3× body circumference. Three to four pairs of rectangle genital markings in 17/18 and presetal xix–xxi in line with male porophores.

Internal characters. Septa 5/6/7/8 thickened, 8/9/10 absent, 10/11/12/13 thin. Oesophageal gizzard in viii–x. Intestinal origin at xv; caeca absent. Last hearts in xiii. Pharyngeal micronephridia developed in anterior faces of 5/6/7. Lymph glands absent. Typhlosole simple, lamelliform.

Spermathecae paired in vii–ix. Spermathecal ampulla small, elongated oval-shaped; duct extremely reduced, somewhat absent. Diverticulum much shorter than ampulla, directly attached to the base of the spermathecal duct. Accessory glands invisible.

Holandric. Testis sacs separated in x–xi, ventrally. Seminal vesicles well-developed, paired in xi–xii. Ovaries in xiii; oviduct invisible. Prostate glands poorly lobuled, paired in xvi–xix; prostatic ducts long, cylindrical and coiled at distal end. Accessory glands invisible.

Entymology. Named after the type locality, Ta Bhing Commune.

Habitats. Polypheretima tabhingensis , new species, was commonly found in natural forests (10–30 cm soil depth) and regenerated forests (0–30 cm soil depth) in Ta Bhing Commune.

Remarks. The new species is also keyed to the bifaria species-group with characters of simple male pores, spermathecal pores in intersegmental furrows, and holandry ( Easton, 1979).

The new species is fairly similar to P. kyhaensis ( Thai, 1996) reported from Nui Thanh District, Quang Nam Province in holandry, simple male pores and the arrangement of genital markings in the male pore region ( Fig. 4 ). However, P. tabhinhensis , new species, has three pairs of spermathecal pores in 6/7/8/9, genital markings paired in 17/18 and presetal xix–xxi, in line with male pores, last hearts in xiii, testes sacs separated, spermathecal ducts extremely short, somewhat totally reduced, and last micronephridia in anterior face of 6/7. In contrast, P. kyhaensis has 4 pairs of spermathecal pores in 5/6/7/8/9, genital markings paired in xvii–xxi including 4 pairs in xviii, last hearts in xii, testes sacs connected, spermathecae heart-shaped with short ducts, and last micronephridia in anterior face of 7/8.

Among bifaria -species group, the new species is also fairly similar to P. sempolensis Easton, 1979 and P. monticola ( Beddard, 1912) in holandry and having simple male pores and genital markings in the male region except in xviii. However, P. tabhinhensis , new species has spermathecal pores in 6/7/8/9 (vs. 5/6/ 7 in P. sempolensis and 5/6/7/8/ 9 in P. monticola ). Furthermore, P. tabhinhensis , new species differs from P. sempolensis in having last hearts in xiii (vs. in xii) and absence of pseudovesicles (vs. presence in xiv). P. tabhinhensis is distinguishable from P. monticola in having short and robust diverticulum (vs. narrow and coiled).

Regarding the arrangement of genital markings, P. tabhingensis , new species, is also similar to P. alba Nguyen, 2016 and P. elongata ( Perrier, 1872) , both from Vietnam, and P. mindanaoensis Aspe & James, 2015 from Philippines in having genital markings paired in xvii, xix–xxi (or xxii). However, P. tabhinhensis differs from the other three species in being bithecate in each thecal segment and having spermathecal pores paired in 6/7/8/9 and no copulatory pouches whereas the other species are polythecate with copulatory pouches.

Figures

Fig. 3. Polypheretima tabhinhensis, new species, holotype. A1, A2, ventral view of male pores region; B1, B2, spermathecae; C1, C2, prostatic glands; D, testis sacs (ts) and seminal vesicles (sv); E, ventral view of spermathecal region; F, male pore cross section slide; G, genital marking cross section slide; H, body wall cross section slide. Scale bar: 1 mm.

Fig. 4. Polypheretima kyhaensis (Thai, 1996) redrawn following the original description (Thai, 1996). A, ventral view of male pore region; B, lateral view of spermathecal region; C, spermathecae; D, testis sacs (ts), seminal vesicles (sv), and ovaries (ov). Scale bar: 1 mm.