Metaphire haui, 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 : 223-225

Metaphire haui , new species

( Figs. 1 , 2 )

Material examined. Holotype: 1 mature ( CTU-EW.172. h01), regenerated forests (10°31′33.0″N, 107°09′44.8″E), Dinh Mts, Tan Hung District, Ba Ria city, Ba Ria-Vung Tau Province, 25 m asl, 26 October 2016, coll. Nguyen Phuc Hau. Paratypes: 4 matures ( CTU-EW.172.p02) same data as holotype; 2 matures ( CTU-EW.172.p03), bushes near the road (10°29′58.0″N, 107°08′31.0″E), Kim Dinh commune, Ba Ria city, Ba Ria-Vung Tau Province, 27 October 2016, coll. Nguyen Phuc Hau.

Non-types: 4 immatures ( CTU-EW.172.p04), Acacia plantations (10°31′33.0″N, 107°09′44.8″E), Hac Dich commune, Tan Thanh District , Ba Ria-Vung Tau Province, 25 m asl, 26 October 2016, coll. Nguyen Phuc Hau.

Diagnosis. Medium-sized worm, length 107–165 mm, diameter 5.3–5.9 mm, unpigmented except light yellow clitellum. Prostomium epilobous. First dorsal pore in 7/8. Three pairs of spermathecal pores in dorsally 6/7/8/9. Male porophore disc-shaped, slightly elevated; male pores located inside copulatory pouches in the setal ring of xviii. Two pairs of genital markings in xvii and xix, in line with the openings of copulatory pouches. Holandric. Intestinal caeca simple. Septum 8/9 thick, but 9/10 absent.

Description. Body cylindrical, medium size; length 107–165 mm, average diameter 5.3–5.9 mm, weight 2.4–3.5 g, segments 101–205. Body transparent, uniformly unpigmented except light yellow clitellum. Prostomium ⅓ epilobous. First dorsal pore in 7/8. Setae perichaetine, pre-clitellar setae stouter and sparser than post-clitellar ones; setal number 65–87 in viii, 108–130 in xxx, 20–25 between male porophores in xviii; setal distance: aa = ab, zz=zy. Clitellum close, xiv–xvi, without dorsal pores and setae. Female pore single, in midventral xiv.

Three pairs of spermathecal pores located dorsally in intersegments 6/7/8/9. No genital markings in the spermathecal region.

Male porophore disc-shaped, slightly elevated from body wall; male pores located inside the copulatory pouches on the setal ring xviii; ventral distance between two openings of copulatory pouches about 0.3× body circumference. Two pairs of slightly elevated, disc-shaped genital markings on setal rings of xvii and xix, in line with the openings of copulatory pouches.

Septa 5/6/7/8/9 thick, 9/10 thin, 10/11/12/13 slightly thick. Oesophageal gizzard within viii–x. Intestinal origin at xv; caeca simple, originating at xxvii and extending anteriorly to

xxiv or xxv. Last hearts in xiii. Pharyngeal micronephridia developed 5/6/7. Typhlosole simple, lamelliform. Lymph glands absent.

Three pairs of spermathecae in vii–ix. Ampulla mushroomshaped, ducts robust, somewhat longer than ampulla, and enlarged basally. Diverticula twice longer than ampulla, directly attached to the base of ampulla duct; seminal chamber poorly developed. 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 in 12/13. Ovisac invisible. Prostate glands deeply lobuled, paired in xvii–xx; ducts long, coiled and attached to copulatory pouches which are highly elevated from body wall. Two pairs of large accessory glands in xvii and xix.

DNA barcode. A partial sequence of the mitochondrial gene cytochrome oxidase subunit I (COI) was uploaded to GenBank with the accession number MK902663 .

Variation. One paratype specimen lacks spermathecal pore in the left side of intersegment 6/7.

Etymology. The new species, Metaphire haui , is named in honour of Mr. Nguyen Phuc Hau, who collected the type specimens.

Remarks. Metaphire haui , new species, is classified into the Metaphire peguana group characterised by having spermathecal pores in 6/7/8/9 and two pairs of genital markings in xvii and xix, in line with the openings of copulatory pouches ( Sims & Easton, 1972). However, it differs from other known species in spermathecal pores located dorsally, first dorsal pore in 7/8, presence of thin septum 8/9/10, genital markings on xvii and xix, whereas other peguana species have spermathecal pores on ventral or lateroventral side, first dorsal pore in 12/13, absence of septum 8/9, and genital markings located in segmental furrows 17/18 and 18/19.

The new species is also similar to Metaphire posthuma ( Vaillant, 1868) in having septum 8/9, two pairs of genital markings in xvii and xix, absence of genital markings in spermathecal region, and simple intestinal caeca. Metaphire haui , new species, is distinguished from M. posthuma in having three pairs of spermathecal pores in dorsal intersegments 6/7/8/9 (vs. four pairs in ventral intersegments 5/6/7/8/9), first dorsal pore in 7/8 (vs. 12/13), connected testis sacs (vs. separated testis sacs), larger size (107–165 mm vs. 67–101 mm in length; 5.3–5.9 mm vs. 4.0– 4.8 mm in diameter), and being more segmented (101–205 vs. 98–119 segments).

Metaphire haui , new species, is also similar to Metaphire nhuongi Nguyen, 2016 , in having two pairs of genital markings in xvii and xix, no genital markings in spermathecal region, simple intestinal caeca. However, the new species has three pairs of spermathecal pores in dorsal intersegments 6/7/8/9, first dorsal pore in 7/8, pharyngeal micronephridia in 5/6/7, presence of septum 8/9/10, connected testis sacs, and absence of lymph glands, whereas M. nhuongi has four pairs of spermathecal pores in ventrolateral intersegments 5/6/7/8/9, first dorsal pore in 12/13, pharyngeal micronephridia in 4/5/6, absence of septum 8/9, separated testis sacs, and lymph glands in 15/16.

Three species previously recorded in Vietnam, M. amplectens ( Michaelsen, 1934) , M. scitula ( Gates, 1936) , and M. dorsobitheca ( Thai & Huynh, 1992) , also have three pairs of spermathecal pores in dorsal intersegments 6/7/8/9. However, M. haui , new species, is distinguished from those species by the presence of two pairs of genital markings in xvii and xix, first dorsal pore in 7/8, thick septum 8/9. On the contrary, those species do not have genital markings in the male region, first dorsal pore in 10/11, and absence of septa 8/9/10. In addition, the new species is similar in size to M. scitula (length 107–165 mm, diameter 5.3–5.9 mm vs. length 100–120 mm, diameter 5 mm), but it is larger than M. amplectens and M. dorsobitheca (107–165 mm vs. 44 mm and 54 mm in length; 5.3–5.9 mm vs. 2–3 mm in diameter, 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. 2. Metaphire haui, new species, holotype (CTU-EW.172.h01). A1, A2, ventral side of the male region; B1, B2, left prostate gland; C1, C2, intestinal caecum; D, testis sacs and seminal vesicle; E1, E2, dorsal side of spermathecal region; F1, F2, left spermathecae; G, genital markings, transverse body section; H, male copulatory pouches, transverse body section. Scale bar = 1 mm.