Metaphire songbeensis, Nguyen & Nguyen & Lam & Nguyen, 2020

Nguyen, Tung T., Nguyen, Nam Q., Lam, Dang H. & Nguyen, Anh D., 2020, Six new species of the genus Metaphire Sims & Easton, 1972 (Annelida: Oligochaeta: Megascolecidae) from southeastern Vietnam, Raffles Bulletin of Zoology 68, pp. 220-236 : 228-230

Metaphire songbeensis , new species

( Figs. 1 , 5 )

Material examined. Holotype: 1 mature ( CTU-EW.176. h01), banana garden (11°45′39.0″N, 106°34′38.8″E), Loc Ninh commune, Loc Ninh District , Binh Phuoc Province, 85 m asl, 26 October 2017, coll. Luong Thi Huynh Tien. Paratypes: 9 matures ( CTU-EW.176.p02), same data as holotype .

Non-types: 13 matures ( CTU-EW.176.03), same data as holotype; 8 matures ( CTU-EW.176.04), bushes (11°17′41.2″N, 106°24′22.1″E), Dau Tieng town, Dau Tieng District , Binh Duong Province, 53.4 m asl, 27 October 2017, coll. Dinh So Na.

Diagnosis. Small-sized worm, length 91–133 mm, average diameter 3.4–6.4 mm. Prostomium epilobous. First dorsal pore in 9/10. Four pairs of spermathecal pores in dorsal intersegments 5/6/7/8/9. No genital markings in spermathecal region. Male pores deeply located inside copulatory pouches in the setal ring xviii. Four to eight pairs of genital markings in xvii, xix, and subsequent segments, but in line with the openings of copulatory pouches. Holandric. Intestinal caeca simple. Septum 8/9 thick, but 9/10 thin.

Description. Body cylindrical, medium size, length 91–133 mm, average diameter 3.4–6.4 mm, weight 1.4–2.1 g, segments 206–236. Body transparent, uniformly unpigmented except orange yellow clitellum. Prostomium epilobous. First dorsal pore in 9/10. Pre-clitellar setae stouter and sparser than post-clitellar ones; setal number 87–156 in viii, 77–124 in xxx, 8–11 between two openings of copulatory pouches; setal distance aa=ab, zz=zy. Clitellum close, xiv–xvi, without setae and dorsal pores. Female single, midventral xiv.

Four pairs of spermathecal pores in dorsal intersegments 5/6/7/8/9; dorsal distance between two spermathecal pores about ⅓ body circumference. No genital markings in spermathecal region.

Male porophores slightly elevated from body wall, almost occupying xviii. Male pores located deeply inside copulatory pouches in the setal ring xviii. Ventral distance between two openings of copulatory pouches about 0.35× body circumference. Genital markings about 4–8 pairs, arranged in xvii, xix, and subsequent segments.

Septa 5/6/7/8/9 thick, 9/10/11/12/13 thin. Oesophageal gizzards after viii. Intestinal origin at xv; caeca simple, paired in xxvii–xxiv. Last hearts in xiii. Pharyngeal micronephridia developed in 5/6/7. Typhlosole simple, lamelliform. Lymph glands absent.

Four pairs of spermathecae in vi–ix. Ampulla large, oval or heart-shaped; duct about ½ ampulla length. Diverticula straight, longer than ampulla, directly attached to the base of ampulla duct; seminal chamber about diverticula length. Spermathecal ducts without nephridia. No accessory glands.

Holandric. Testis sacs well developed, connected in x and xi. Seminal vesicles developed in xi and xii. Ovaries in 12/13, ovisacs invisible. Prostate glands deeply lobuled, paired in xvii–xx; ducts slender and coiled. Accessory glands large, connected to genital markings.

Variations. Specimens collected from Binh Phuoc Province have spermathecal pores located dorsally and 5–8 pairs of genital markings, whereas specimens collected from Binh Duong Province have spermathecal pores located middorsally and only 4 pairs of genital markings.

DNA barcode. A partial sequence of the mitochondrial gene cytochrome oxidase subunit I (COI) was uploaded to GenBank with the accession number MN514952 .

Etymology. The new species, Metaphire songbeensis , is named after the old name, Song Be province, which previously consisted of both Binh Phuoc and Binh Duong provinces.

Remarks. Metaphire songbeensis , new species, is similar to several species of the Metaphire malayana group, such as M. strellana ( Gates, 1949) , M. fovella ( Gates, 1949) , M. malayana ( Beddard, 1900) , M. malayanoides Nguyen & Lam, 2017 , by having four spermathecal pores in 5/6/7/8/9, presence of genital markings in xix and subsequent segments, being holandric, and by having simple caeca. However, the new species is distinguished from these species by the absence of genital markings in spermathecal region, the presence of genital markings in xvii, spermathecal pores located dorsally, and thick septum 8/9, whereas the above species have genital markings in spermathecal region and in xvii (instead of xviii), spermathecal pores located ventrally or lateroventrally, and the absence of septum 8/9.

The new species is also similar to M. posthuma ( Vaillant, 1868) by having genital markings in xvii and xix, and thick septum 8/9. However, it differs from M. posthuma in having spermathecal pores located dorsally (vs. ventrally), first dorsal pore in 9/10 (vs. 12/13), epilobous prostomium (vs. prolobous prostomium), connected testis sacs (vs. separated testis sacs), and the absence of lymph glands (vs. lymph glands starting in 27/28) as well as being more segmented (206–236 vs. 98–119 segments) and slightly larger (91–133 mm vs. 67–101 mm in length; 3.4–6.4 mm vs. 4.0– 4.8 mm in diameter).

Several species recorded in Vietnam also have spermathecal pores on dorsal side, such as M. truongsonensis ( Thai, 1984) , M. amplectens ( Michaelsen, 1934) , M. scitula ( Gates, 1936) , and M. dorsobitheca ( Thai & Huynh, 1992) . Metaphire songbeensis , new species, is distinguished from M. truongsonensis by having 4–8 pairs of genital markings in xvii, xix, and subsequent segments, the first dorsal pore in 9/10 (vs. absence of genital markings in the male region, first dorsal pore in 12/13). The new species is also different from M. amplectens , M. scitula , and M. dorsobitheca in having four pairs of spermathecal pores in 5/6/7/8/9 (vs. three pairs in 6/7/8/9), the presence of genital markings in the male region (vs. absence of genital markings), first dorsal pore in 9/10 (vs. in 12/13). The new species is similar in size to M. scitula (91–133 mm vs. 106–120 mm in length; 3.4–6.4 mm vs. 5 mm in diameter), but larger and more segmented than M. amplectens and M. truongsonensis (91–133 mm vs. 44–52 mm and 54 mm in length; 3.4–6.4 mm vs. 2–3 mm and 2 mm in diameter; 206–236 vs. 90–112 and 76 segments, respectively).

Figures

Fig. 1. Collecting sites in southeastern Vietnam. A, map of Vietnam and component provinces; B, Binh Phuoc Province; C, Ba Ria-Vung Tau Province; D, Binh Duong Province. 1, Metaphire haui, new species; 2, Metaphire bariaensis, new species; 3, Metaphire planatoides, new species; 4, Metaphire songbeensis, new species; 5, Metaphire setosa, new species; 6, Metaphire houlletoides, new species.

Fig.5. Metaphire songbeensis, new species, holotype (CTU-EW.176.h01).A1, A2, ventral side of the male region; B1, B2, left spermathecae; C, dorsal side of spermathecal region; D1, D2, intestinal caecum; E, seminal vesicles; F1, F2, right prostate gland. G, genital markings, transverse body section; H, male copulatory pouch, transverse body section. Scale bar = 1 mm.