Metaphire bariaensis, 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 : 225-227

Metaphire bariaensis , new species

( Figs. 1 , 3 )

Material examined. Holotype: 1 mature ( CTU-EW.169.h01), natural forests, (10°35′36.0″N, 107°06′50.0″E), Bao Quang Mts, Chau Pha commune, Tan Thanh District , Ba Ria-Vung Tau Province, 81.6 m asl, 24 October 2016, coll. Nguyen Phuc Hau. Paratypes: 2 matures ( CTU-EW.169.p02), same data as holotype; 3 matures ( CTU-EW.169.p03), regenerated forests (10°38′21.0″N, 107°05′08.0″E), Dinh Mts, Tan Hung commune, Ba Ria city, Ba Ria-Vung Tau Province, 72–75 m asl, 27 October 2016, coll. Nguyen Phuc Hau.

Diagnosis. Large-medium size, length 141–170 mm, average diameter 6.3–7.6 mm. Prostomium epilobous. First dorsal pore in 11/12. Four pairs of spermathecal pores in ventrolateral intersegments 5/6/7/8/9. Male pores located inside copulatory pouches in the setal ring xviii. Genital markings totally absent. Holandric. Intestinal caeca manicate. Septa 8/9/10 absent.

Description. Body cylindrical, large-medium size; length 141–170 mm, average diameter 6.3–7.6 mm, weight 3.4–6.0 g, segments 89–112. Dorsa light pink and ventra paler, clitellum reddish brown. Prostomium 1/2 epilobous. First dorsal pore in 11/12. Pre-clitellar setae stouter and sparser than post-clitellar ones; setal number 46–62 in viii, 60–81 in xxx, and 6–12 between two openings of copulatory pouches in xviii; setal distance aa> ab, zz> zy. Clitellum xiv–xvi, without setae and dorsal pores. Female pore single, in midventral xiv.

Four pairs of spermathecal pores in ventrolateral intersegments 5/6/7/8/9. No genital markings in spermathecal region. Male pores deeply located inside copulatory pouches in the setal ring xviii; ventral distance between two openings of

copulatory pouches ca. 0.3× body circumference. No genital markings in male region.

Septa 5/6/7/8 thick, 8/9/10 absent, 10/11/12/13 slightly thick. Oesophageal gizzard within viii–x. Intestinal origin at xv; caeca manicate, paired within xxvii–xxiv, distal part somewhat rolling up. 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 heart-shaped, scabrous; ducts shorter than ampulla (about ½ length), cylindrically slender. Diverticula much shorter than ampulla, directly attached to the base of ampulla ducts; seminal chamber oval-shaped. Spermathecal ducts without nephridia. No accessory glands.

Holandric. Testis sacs developed, connected in x–xi. Seminal vesicles well developed in xi–xii. Ovaries well developed on septum 12/13, ovisacs in 12/13 and more developed in 13/14. Prostate glands deeply lobuled, paired in xvi–xx; ducts very short, slightly curved. Accessory glands invisible.

DNA barcode. A partial sequence of the mitochondrial gene cytochrome oxidase subunit I (COI) was uploaded to GenBank with the accession number MK902662 .

Etymology. The new species, Metaphire bariaensis , is named after the Ba Ria-Vung Tau Province where the types were found.

Remarks. The new species can be classified in the Metaphire ignobilis group characterised by having four pairs of spermathecal pores in 5/6/7/8/9, absence of additional copulatory pouches in xix and xx, absence of genital markings in male region, and being holandric ( Sims & Easton, 1972). The ignobilis group currently contains M. feuerborni ( Michaelsen, 1932) , M. ignobilis ( Gates, 1935) , M. tosaensis ( Ohfuchi, 1938) , and M. riukiuensis ( Ohfuchi, 1957) from Japan, M. dalatana ( Michaelsen, 1934) , M. langbiangi ( Michaelsen, 1934) , and M. truongsonensis ( Thai, 1984) from Vietnam, M. seponensis ( Thai & Samphon, 1989) from Laos, and M. trangensis Bantaowong & Panha, 2016 , from Thailand.

Within the ignobilis species group, Metaphire bariaensis , new species, is slightly similar to Metaphire truongsonensis ( Thai, 1984) , M. ignobilis ( Gates, 1935) , and M. trangensis Bantaowong & Panha, 2016 , in having epilobous prostomium, absence of genital markings in spermathecal region, last hearts in xiii, and intestinal origin at xv. However, the new species has manicate intestinal caeca while others have simple caeca. The new species also differs from M. dalatana , M. truongsonensis , and M. seponensis in having spermathecal pores located laterally, first dorsal pore in 11/12, and lobuled intestinal caeca. On the contrary, M. dalatana , M. seponensis , and M. truongsonensis have the first dorsal pore in 12/13, simple intestinal caeca, spermathecal pores located ventrally ( M. dalatana and M. seponensis ) or mediodorsally ( M. truongsonensis ). The new species is also larger than M. dalatana and M. truongsonensis (141–170 mm vs. 52 mm and 80–93 mm in length; 6.3–7.6 mm vs. 2.5 mm and 4.7–4.8 mm in diameter, respectively). It is less segmented than M. truongsonensis (89–112 vs. 110–150 segments), but not different from M. dalatana in number of segments (89–112 vs. 96).

Similarly, Metaphire bariaensis , new species also differs from M. langbiangi in the position of the first dorsal pore (11/12 vs. 12/13), intestinal caeca (ventrally lobuled vs. deeply manicate), body size (141–170 mm in length, 6.3–7.6 mm diameter vs. 67 mm in length, 3 mm diameter). The new species is also distinguished from M. trangensis by having spermathecal pores located lateroventrally, lobuled intestinal caeca, and connected testis sacs, whereas M. trangensis has spermathecal pores on the ventral side, simple intestinal caeca, and separated testis sacs. However, the new species and M. trangensis are not different in body size (141–170 mm in length, 6.3–7.6 mm diameter vs. 120–169 mm in length, 7.3–7.6 mm diameter).

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. 3. Metaphire bariaensis, new species, holotype (CTU-EW.169.h01). A1, A2, ventral side of the male region; B1, B2, right prostate gland; C, lateral side of spermathecal region; D1, D2, spermathecae; E, testis sacs and seminal vesicles; F, male copulatory pouch, transverse body section; G1, G2, intestinal caecum. Scale bar = 1 mm.