Amynthas hauyhowensis Hong and James, 2013

Hong, Yong, James, Samuel W. & Inkhavilay, Khamla, 2013, A new species of earthworm in Amynthas hexathecus species group (Clitellata: Megascolecidae) from the Nam Xam National Protected Area, Laos, Journal of Natural History 48 (5 - 6), pp. 251-256 : 252-254

Amynthas hauyhowensis Hong and James sp. nov.

( Figure 1 )

Type material

Holotype: Clitellate: ( BDNUL 0017 ): Laos, Houaphan Province, Xam Tay district, Nam Xam NPA, South Hauyhow town (20 ◦ 00. 681 ′ N, 104 ◦ 40.410 ′ E), 470 m, natural forest condition with dark soil on limestone, 2 September 2004; Monsri, Vanya colls . Paratypes: three clitellates ( BDNUL 0018 , BDNUL 0019 , BDNUL 0020 ): Same data as for holotype .

Other material

Fifty-three clitellates, same data as for holotype.

Etymology

The species is named for its type locality, Hauyhow.

Diagnosis

Spermathecal pores five pairs in 4 / 5–8 / 9, secondary male pore equatorial in XVIII at 11th setal lines, paired invaginated genital papillae postsetal on XVII anterior to male pores, caeca manicate.

Description

Dimensions 62–80 mm, by 4.0– 4.4 mm at segment X, 3.5–4.5 mm at segment XXX, 4.4–4.5 mm at clitellum; body cylindrical, segments 59–78. Setae numbering 56–62 at VII, 50–62 at XX, 11–15 between male pores, slightly more widely spaced ventrally, setal formula AA: AB: ZZ: YZ = 3: 4: 3: 3 at XIII. Female pore single on XIV within a circular porophore 0.3 mm in diameter. Prostomium epilobic with tongue open. Very dark brown to black anterior–dorsal pigment, also pigmented in ventral I–IX, lighter on setal rings and post-clitellar segments, clitellum coffee coloured, formalin preservation. First dorsal pore at 12 / 13. Clitellum annular XIV–XVI; setae invisible externally.

Secondary male pores equatorial in XVIII at 11th setal line, 0.14–0.24 circumference apart ventrally; paired invaginated genital papillae postsetal on XVII anterior to male pores, both pores in transverse sphincter-like slits 0.3 mm in diameter. Primary male pores within shallow invagination confined to circular body wall muscle layer. Spermathecal pores five pairs in 4 / 5–8 / 9, conspicuous, 0.14–0.26 ventral circumference apart from each other.

Septa 5 / 6–6 / 7 thick, 7 / 8 thin, 8 / 9–9 / 10 absent, 10 / 11–12 / 13 slightly muscular. Gizzard in VIII–X. Intestine begins in XV, lymph glands not found. Typhlosole small from XXVII. Intestinal caeca manicate, originating XXVII, extending anteriorly about to XXIII each containing four to eight small finger-shaped lobes. Hearts oesophageal in X–XII. Male sexual system holandric, testes, funnels in ventrally joined sacs in X, XI. Seminal vesicle large two pairs in XI, XII, small round dorsal lobes in shallow clefts. Prostates XVIII dense three to five lobes extending from XVII to XXII, duct large, muscular, coiled in two or three complete spiral clockwise left side, anticlockwise right side; from gland up to muscular spiral section, a short non-muscular duct section spirals in the reverse direction on each side.

Ovaries in XIII. Paired spermathecae in V–IX, each ampulla ovate to blocky, duct shorter than ampulla. Diverticulum with short straight stalk, elongate chamber coiled and tightly bound into approximately oval outline, no nephridia on spermathecae ducts.

Remarks

We are considering the very shallow invagination of the male pores and genital papillae as belonging to Amynthas , because there is no resemblance to the coelomic copulatory pouches said to be held in common between Metaphire and Pheretima in Sims and Easton (1972). Furthermore those authors state that their Amynthas concept was simplified by deliberately excluding six species clearly clustering with Amynthas in their phenetic analysis, and transferring said species to Metaphire . We see no reason to make it more so. Amynthas hauyhowensis sp. nov. bears character states in common with several Lao Amynthas species in the aeruginosus -group (spermathecal pores 7 / 8 / 9), notably the mirror-image coiled prostatic ducts and lack of lymph glands on the intestine ( Hong 2010). Amynthas hauyhowensis sp. nov. keys to the hexathecus group in Sims and Easton (1972). No such Lao earthworm species have been recorded ( Thai and Samphon 1991a). The position of spermathecae in V–IX is unusual in Laos, and very uncommon in Amynthas generally ( Sims and Easton 1972). Of the 10 species listed by Sims and Easton (1972) in the hexathecus group, four are referable to Amynthas based on somatic characters. The remaining species with the same spermathecal location are Amynthas brevicinctus ( Gates, 1958) , Amynthas flustrellus ( Gates, 1949) , Amynthas hexathecus ( Benham, 1896) , Amynthas polytoreutus ( Michaelsen, 1928) , Amynthas scholasticus ( Goto and Hatai, 1898) , and Amynthas solomonis ( Beddard, 1899) . Amynthas scholasticus has its last hearts in XIII, fewer setae and only four pairs of spermathecae in V–VIII. Amynthas brevicinctus , A. solomonis , A. flustrellus and A. polytoreutus all have superficial male pores, and each differs in genital marking numbers and locations, with none being invaginated. The last two also have their last hearts in XIII. Amynthas hexathecus has far more setae (∼ 100 in post-clitellar segments) and genital papillae in XVII, XIX and XX ( Table 1).

Figures

Figure 1. Amynthas hauyhowensis sp. nov. (A) ventral view; (B) spermathecae; (C) intestinal caeca; (D) prostate gland. Scale bars = 2.5 mm (A), 2 mm (B–D).