Amynthas kume Blakemore, 2022

Blakemore, Robert J., Miller, Shawn & Lim, Shu Yong, 2022, Two New Species of Japanese Earthworms (Annelida, Oligochaeta, Megadrilacea, Megascolecidae) Update Biodiversity on Okinawa and at Lake Biwa to ca. 30 Species, Bulletin of the Kanagawa Prefectural Museum (Natural Science) 51, pp. 95-104 : 95-97

Amynthas kume Blakemore , sp. nov.

Distribution: Mt Aratake, Kumejima Island, Okinawa, Japan (26°18'38.3"N 126°47'15.0"E); also reported from Mt Daruma by S. Miller (RJB pers. comm.).

Etymology: The species name is derived from its island location (noun in apposition).

Material examined (see Figs. 3–4 ): Holotype (H), LBM FY 2015-11-1 mature, dissected (DNA tissue samples #K3-5.1, #K5.2 re-sent to DNA lab via KPMNH) ; Paratype 1 (P1) FY 2015-11-2 (DNA #K1); Paratypes 2–3 (P2–4) FY20015-11-3–4; all collected 15th Feb., 2016 (by RJB) from under forest litter or logs beside mountain road .

Description: Large and brown with yellow/buff intersegmental bands (i.e., striped). Lengths, H 190+ 20 mm (posterior amputee = 210 mm); P 1, 220 mm; P 2, 205 mm; P 3, 190 mm. Prostomium epi-lobous. First dorsal pore 11/12. Setae about 60 on segment 12. Spermathecal pores in line with male pores four pairs in 5/6/7/8/ 9 in semicircular pits. Clitellum 14–16. Female pore on 14. Male pores superficial in small circular patches on 18 with about 14 (H) or 12 (P1) setae intervening between pores. No genital markings (GMs) found. Septa 8/9/10 absent around muscular gizzard in 8. Spermathecae four pairs in 6–9 each with single diverticulum about as long as ampulla. Seminal vesicles in 11 and 12. Ovaries and last hearts in 13. Small ovisacs in 14. Intestine from 15. Racemose prostates in 18. Intestinal caeca smooth and simple in 27–24. No glands found near spermathecal pores.

Diagnosis: Other megascolecid species currently reported from Okinawan Islands with four pairs of spermathecae in segments 5/6/7/8/9 are exotic Amythas corticis (Kinberg, 1867) species-complex and A. micronarius (Goto & Hatai, 1898) parthenogenetic species-complex with A. obtusus (Ohfuchi, 1957) currently in its synonymy (see Blakemore, 2012a, b, 2020). All these taxa have genital markings (GMs). A recent taxon on Okinawa Island is A. cucurbita Azama & Ishizuka, 2018 (emend.) that, however, is smaller at <75 mm and also has markings around its male pores. Quadrithecate Metaphire riukiuensis (Ohfuchi, 1957) has seminal grooves in 17–19 amongst other differences while the M. formosae (Michaelsen, 1922) group is mainly from Taiwan and adjacent islands. The present specimens thus appear unique to Kumejima representing a new species. It is unusual for an Amynthas to lack GMs, a trait more common to Metaphire that typically has fewer spermathecae and eversible penes to compensate.

Other earthworms found on the island in this study were the exotic lumbricid of American origin: Bimastos parvus (Eisen, 1874) (LBM FY 2015-11-5) from Gushikawa Castle, Kumejima collected 16th Feb., 2016 from under rocks as a new record for Okinawa (published in Blakemore, 2016a), and Asiatic exotic Pithemera bicincta (Perrier, 1875) (LBM FY 2015-11–6 providing tissue samples #K2 & K6 – KPM-NJL 82) that had been previously reported from Okinawa, not least by Ohfuchi (1957a: 254), Easton (1981) and Blakemore (2002, 2003, 2020a,b; Blakemore et al., 2007). Despite Ito et al. ’s (2019) claim, Ohfuchi’s description precisely matches P. bicincta and he clearly states: “ Intestine begins in XIV, and a pair of intestinal caeca which are very short, are less developed compared with many other species; broad, apparently rudimentary, or may be altogether absent.. ” but he has then inadvertently added a transcription error with: “ ..commences (sic) in XXVI or XXVII.. ” (in actuality its small caeca are often paired in 22). As for B. parvus , it is relatively common on the main islands of Japan and Kobayashi (1941) reports it from “ DZ ± ‼ ” that is translated as Ama mura, possibly on Nakanoshima in Oki Islands, Shimane-ken, but it has not been previously found on Okinawan Islands.

Figures

Fig.3. Amynthas kume sp. nov. from Kumejima Island (photo courtesy of Shawn Miller).

Fig. 4. Amynthas kume sp. nov. Holotype sketch with spermathecae and caecum.