Metaphire kiengiangensis Nguyen & Trinh, 2015

Nguyen, Tung. T., Trinh, Binh K. T., Le, Nhan V. & Nguyen, Anh D., 2015, On the polythecate earthworms of the genus Metaphire (Oligochaeta: Megascolecidae) from Vietnam, with descriptions of three new species, Raffles Bulletin of Zoology 63, pp. 461-470 : 461-465

Metaphire kiengiangensis Nguyen & Trinh , new species

( Fig. 1 , Tables 1, 3)

Examined material. Holotype: 1C (CTU.EW019–h01), plantation of Hopea and other trees, Lai Son Island , Kien Hai District, Kien Giang Province, Vietnam (09°48’21.6 N;

104°38’01.1 E), elevation of 81 m a.s.l., 15 November 2013, coll. Trinh Thi Kim Binh. Paratypes: 10C (CTU.EW019–p02) same data as for holotype; 3C (CTU.EW019–p03) fruit tree garden, on the way to Bang Beach , Lai Son Island, Kien Hai District, Kien Giang Province, Vietnam (09°48’32.4 N; 104°39’23.0 E), 14 October 2014, coll. Trinh Thi Kim Binh.

Further material. 13C (CTU.EW019–p04) mango garden, Hon Dat Mountain , Hon Dat District, Kien Giang Province, Vietnam (10°06’37.6 N; 104°53’06.2 E), 13 November 2010, coll. Nguyen Thanh Tung.

Diagnosis. Large-size worm, length 176–280 mm, diameter 6.3–8.1 mm. Setae perichaetine; pre-clitellar setae stouter and sparser than post-clitellar setae; setae distance aa = ab, zz = zy. First dorsal pore in 12/13. Multiple spermathecal pores ventral in intersegments 6/7/8/9. Two pairs of genital markings in intersegments 17/18 and 18/19. Holandric. Intestinal caeca simple. Septa 8/9/10 absent.

Etymology. “ kiengiangensis ” after the name of province where type material was found.

Description. External characters: Body cylindrical, large size; length 176–280 mm, diameter 6.3–8.1 mm, weight 6.0– 19.3 g. Dorsum darkish grey, but ventrum paler; body generally greenish shining, especially for living specimens. Prostomium 2/3 epilobous. First dorsal pore in 12/13. Setae perichaetine; pre-clitellar setae stouter and sparser than post-clitellar setae, 31–39 in v, 42–53 in viii, 81–88 in xxv, 72–88 in xxx, 10–18 between male porophores in xviii; setal distance aa = ab, zz = zy. Clitellum annular, xiv–xvi, greyish brown, smooth and without setae and dorsal pores. Female pore single, mid-ventral in xiv.

Spermathecal pores round and small, multiple, ventral in intersegments 6/7/8/9. No genital markings in spermathecal region.

Male pores deeply located inside copulatory pouches in xviii; ventral distance between male porophores about 0.3× body circumference. Two pairs of genital markings present in intersegments 17/18 and 18/19; anterior pair in 17/ 18 in front of male pores, posterior pair in 18/19 slightly medial to male pores.

Internal characters: Septa 6/7/8 thickened, 8/9/10 absent, 10/11 thin, and 11/12/13 slightly thickened. Oesophageal gizzard within viii–x. Intestinal origin at xv or xvi; caeca simple, within xxvii–xxvi. Last hearts in xiii. Pharyngeal micronephridia developed in 4/5 and well developed in

5/6. Lymph glands present from xv. Typhlosole simple, lamelliform.

Spemathecae variable, 30–46 altogether in intrasegmental 6/7/8/9: 8–14 in 6/7, 10– 18 in 7/8 and 11–16 in 8/9 ( Table 1). Spermathecal ampulla subcylindrical; duct about 1/3 ampulla in length. Diverticula irregularly sinusoidal, folded onto itself several times, longer than ampulla; duct attached to base of ampulla. No accessory glands.

Holandric. Testis sacs not separated. Seminal vesicles well developed within xi–xii. Oviduct on septum 12/13 posteriorly; ovaries not visible. Prostate glands racemose, paired in xv–xx; prostatic ducts U-shaped, slightly getting smaller distally. Two pairs of accessory glands present, highly elevated towards body coelom, and being covered with thick muscle layer.

Habitat and ecology. All specimens of this new species collected in October and November were adults and having clitellum. No adult specimens have been found in the other months of the year. The species was found in light-clay soils, especially in mango gardens in mountain.

Remarks. Only two populations have been found in Kien Giang province, one in mainland mountains of Hon Dat District, the other in Lai Son island of Kien Hai District. Both populations have same stable characters, such as prostomium 2/3 epilobous, first dorsal pore in 12/13, multiple spermathecal pores in 6/7/8/9, presence of copulatory pouches, two pairs of genital markings in 17/18 and 18/19, intestinal caeca simple, and holandric. The first population (n=13) differs from the second (n=14) in shorter (95–160 mm vs 176–280 mm in length; 4.7–5.6 mm vs 6.3–8.1 mm in diameter), lighter (1.7–3.3 g vs 6.0– 19.3 g), clitellum (incomplete xiv–2/3xvi vs complete xiv–xvi). The mainland population has 43–54 spermathecae: 7–16 in 6/7, 16– 21 in 7/8, 16– 22 in 8/9; ampulla mango-shaped, diverticula shorter than ampulla and directly attached to duct of ampulla. On the contrary, the island population has 30–46 spermathecae: 8–14 in 6/7, 10– 18 in 7/8, 11– 16 in 8/9; ampulla cylindrical; diverticula longer than ampulla and directly attached to base of ampulla.

The new species obviously belongs to the multitheca -group containing only two species, Metaphire multitheca ( Chen, 1938) and M. dipapillata ( Thai et Tran, 1986) . The species shares with two species multiple spermathecal pores per segment. M. multitheca ( Chen, 1938) differs from the new species in having two pairs of genital markings in front of and behind male porophores in xviii, multiple spermathecal pores on posterior border of segments vi, vii and viii. M. dipapillata ( Thai et Tran, 1986) differs from the new species in having four thecal segments, multiple spermathecal pores in intersegments 5/6/7/8/9, and having a pair of round genital markings in intersegment 17/18. Marker characters of three species are presented in Table 3.

Figures

Fig. 1. Metaphire kiengiangensis, new species, holotype and specimen 13 (CTU.EW019-p04). A, B, male pore region (mp = male pore; gm = genital markings): A, mainland population; and B, island population; C, D, spermathecae, left side (am = ampulla; dv = diverticula): C, mainland population; and D, island population; E, prostate gland (ag = accessory gland); F, intestinal caeca; G, H, transverse body section of segment xviii: G, male pore; and H, accessory glands. Scale bars = 1mm.