Amynthas erroneous, Nguyen, Anh D. & Nguyen, Tung T., 2015

Nguyen, Anh D. & Nguyen, Tung T., 2015, Notes on Metaphiremultitheca (Chen, 1938) (Oligochaeta, Megascolecidae) recorded from Vietnam, with descriptions of two new species, ZooKeys 506, pp. 127-136 : 128-129

Taxon classification Animalia Opisthopora Megascolecidae

Amynthas erroneous sp. n. Fig. 1, Table 1

Pheretima multitheca multitheca - Nguyen 1994: 53; Pham 1995: 68; Huynh 2005a: 89; Huynh 2005b: 20; Nguyen and Tran 2008: 185; Pham 2010: 63.

Non Pheretima multitheca Chen, 1938: 383, fig. 2.

Material examined.

Holotype. 1C ( CTU–EW 071.02-h01) taro garden, Duc Pho commune (108°57'9"E, 14°48'18"N), elevation of 5 m a.s.l., Pho Minh district, Quang Ngai province, Vietnam, 15 April 1995, coll. Huynh Thi Kim Hoi. Paratypes. 13C ( CTU–EW 071.02-p02) same data as for holotype. Further material. 8C ( SORC–V.153.01) garden, Duc Pho town, Pho Minh, Quang Ngai, 15 April 1995, coll. Huynh Thi Kim Hoi. Fixed in formalin.

Diagnosis.

Medium-size worm. First dorsal pore in 11/12 or 12/13. Prostomium 1/3 epilobous. Multiple spermathecal pores lateroventral in intersegments 5/6/7/8/9. Male pores located in xviii, without copulatory pouches. Two pairs of crescentic genital markings in xviii. Holandric. Testis sacs not separated. Intestinal caeca simple, within xxvii-xxv. Septa 8/9/10 absent.

Etymology.

To emphasize the misidentification of the species as Pheretima multitheca .

Description.

External characters: Body cylindrical, medium size. Length 112-150 mm, diameter 3.81-5.0 mm, segments 119-150, weight 1.61-2.94 g. Body coloration uniformly brown. Setae perichaetine, more concentrated ventrally; preclitellar setae sparser than postclitellar setae, 42-46 in v, 37-65 in viii, 61-71 in xxv, 42-72 in xxx, 10-16 between male porophores in xviii; setal distance aa=2ab, zz=1.5zy. First dorsal pore in 12/13, rarely in 11/12. Prostomium ⅓ epilobous. Clitellum annular, xiv- ¾ xvi, darkish brown, smooth and without setae and dorsal pores. Female pore single, mid-ventral in xiv.

Spermathecal pores round and small, multiple, lateroventral in intersegments 5/6/7/8/9, sometimes invisible. No genital markings in spermathecal region.

Male pores located in porophores in xviii, without copulatory pouches; ventral distance between male porophores about 0.28 × body circumference. Two pairs of large, crescentic genital markings in xviii, located in front of and behind male porophores.

Internal characters: Septa 6/7/8 thickened, 8/9/10 absent, and 10/11/12/13 relatively thickened. Oesophageal gizzard after 7/8, pear-shaped. Intestinal origin at xv; caeca simple, within xxvii–xxv. Last hearts in xiii. Pharyngeal micronephridia developed in 4/5/6. Lymph glands present from xvii, rarely xvi, and lobulated. Typhlosole simple, lamelliform.

Spemathecae variable, 21-27 altogether in 5/6/7/8/9: 2-4 in 5/6, 4-6 in 6/7, 5-7 in 7/8 and 6-8 in 8/9. Spermathecal ampulla large, oval; duct about ⅓, rarely as much as ½ the length of the ampulla. Diverticula irregularly sinusoidal, folded onto itself several times, enlarged distally, about half length of ampulla; stalk attached to base of duct of ampulla. No accessory glands.

Holandric. Testis sacs not separated, developed in x and xi. Seminal vesicles well developed within xi–xii, yellowish white. Oviduct poorly developed on septum 12/13 posteriorly; a pair of ovaries in xiii. Prostate glands racemose, paired in xvii–xix; prostatic ducts C-shaped. Two accessory glands present.

DNA.

COI barcode data not yet available.

Habitat and ecology.

The species was found in soils in which old growth trees had been grown. No other ecological data had been recorded.

Distribution.

Previous misidentifications of Pheretima multitheca multitheca were from Quang Tri (Quang Tri town); Thua Thien Hue (Huong Tra; Hue; Nam Dong; Phu Loc); Danang; Quang Nam (Que Son); Quang Ngai (Quang Ngai city; Duc Pho); Binh Dinh; Dak Nong (Ta Dung Mts.) ( Nguyen 1994, Pham 1995, 2010, Huynh 2005a, 2005b, Nguyen and Tran 2008).

Remarks.

This new species was previously misidentified as Pheretima multitheca multitheca Chen, 1938 (= Metaphire multitheca ), which was originally known only from Hainan Island. Both species share multiple spermathecal pores per segment and presence of intestinal caeca. However, Amynthas erroneous sp. n. has multiple spermathecal pores in intersegments 5/6/7/8/9, and lacks copulatory pouches while Metaphire multitheca (Chen, 1938) has multiple spermathecal pores located behind setal rings of segments vi, vii, viii, and presence of copulatory pouches. The new species is also fairly similar to Metaphire multitheca dipapillata (Thai & Tran, 1986), now Metaphire dipapillata stat. n.; both species have multiple spermathecal pores in intersegments 5/6/7/8/9, and genital markings associated with the male pores. However, Amynthas erroneous sp. n. lacks copulatory pouches and has two pairs of crescentic genital markings in xviii, whereas Metaphire dipapillata has copulatory pouches and only a pair of genital markings in 17/18, located in front of male porophores. Marker characters of three species, Amynthas erroneous , Metaphire dipapillata and Metaphire multitheca are presented in Table 1.

The new species is also distinguished from other 5/6/7/8/9 polythecate species such as Polypheretima bifaria (Michaelsen, 1924) from New Guinea, Polypheretima polytheca (Beddard, 1900b) from Malay penisula, Polypheretima koyana Michaelsen, 1934 from Sarawak, and Metapheretima elrondi Easton, 1979 from New Guinea by having intestinal caeca. Althought it shares with Amynthas bleckwenni (Ude, 1925) from Borneo the multiple spermathecae at 5/6/7/8/9, and having intestinal caeca, the new species differs from Amynthas bleckwenni in having two pairs of crescentic genital markings in front of and behind male pores on xviii.

We herein raised the subspecies Metaphire multitheca dipapillata to full rank as Metaphire dipapillata stat. n., and also restore Metaphire multitheca multitheca as Metaphire multitheca .

The new species is widely distributed in central parts and highlands of Vietnam. Surprisingly, it has never yet been found in northern and southern Vietnam.