Amynthas longicaeca Bantaowong & Panha, 2014

Bantaowong, Ueangfa, Somniyam, Pattana, Sutcharit, Chirasak, James, Samuel W & Panha, Somsak, 2014, Four new species of the earthworm genus Amynthas Kinberg, 1867, with redescription of the type species (Clitellata: Megascolecidae), Raffles Bulletin of Zoology 62, pp. 655-670 : 660-662

Amynthas longicaeca Bantaowong & Panha , new species

( Figs. 4 , 11C, D ; Table 1)

Material examined. Holotype: One adult ( CUMZ 3304 ) Phu Lan Kha National Park, Nong Bua Daeng, Chaiyaphum, Thailand, (16°00ʹ01.70ʺN, 101°52ʹ35.40ʺE), 660 m in elevation, coll. S. Panha, R. Chanabun, P. Tongkerd and W. Siriwut, 17 September 2011. One adult paratype ( CUMZ 3305 ), same collection data as for holotype.

Diagnosis. Large; length 230–278 mm. Male pores paired, superficial in segment XVIII, somewhat convex, with a large crescent shape genital marking. Spermathecae three pairs, in segments VII–IX, ampulla oval, with duct shorter than ampulla. Diverticulum very small with ovate knob, length less than half of ampulla. Intestinal caeca long, simple. First dorsal pore in 12/13. Prostate glands large, prostatic duct flanked by large sessile glandular masses on body wall.

Description of holotype. Dimensions; 278 mm by 10.1 mm at segment VII, 9.2 mm at segment XX, 8.2 mm at clitellum; body cylindrical with 160 segments. Setae regularly distributed around segmental equators, numbering 53 at VII, 81 at XX, 25 between male pores, setal formula AA:AB:ZZ:ZY=1:1:2:1 at XIII. Single female pore at XIV. Prostomium epilobic. First dorsal pore at 12/13. Clitellum annular XIV–XVI with no setae.

A pair of male pores located ventro-lateral in XVIII, 0.40 circumference apart ventrally, distance between male pores 9 mm. Male pores superficial, somewhat convex, located between small crescent genital markings. The paired median markings large crescent shape, 3–4 setal intervals distant from male aperture and separated from each other midventrally by a distance about equal to 8 intersetal intervals. Spermathecal pores three pairs, transverse slits, in furrows 6/7–8/9, ventral, paired pores about 0.45 body circumference ventrally apart, distance between spermathecal pores 10 mm. No genital markings in the spermathecal pores region.

Septa 5/6–7/8 thick, 8/9–9/10 absent, 10/11–12/13 thin. Gizzard large behind 7/8, intestinal origin in XV; the intestinal caeca simple and long located in XXVII to XXIV, when fully extended they reach as far forward as the prostate duct at XVIII. Typhlosole simple, one third intestinal diameter beginning at XXVII. No lymph glands observed. Oesophageal hearts four pairs in X–XIII. Holandric; testes and funnels in X and XI. Seminal vesicles paired in XI–XII, large. Prostate glands well developed, separated into two major lobes, extending XVI–XXI. Prostate duct long, slender and hairpin shape, flanked by large sessile glandular masses on body wall.

Ovaries in XIII. Spermathecae three pairs in VII–IX. The ampulla large oval, with duct shorter than ampulla, diverticulum small ovate knob, stalk very short, nephridia present on diverticulum and on segmental chambers in VII and VIII.

Variation. The holotype measures 278 mm body length with 160 segments; the paratype is 230 mm long with 115 segments.

Etymology. This species was named after the characteristic long intestinal caeca.

Distribution. The new species is known only from the type locality.

Habitat. Top soil at about 20 cm depth in the dipterocarp forest at elevation 660 meters of Phu Lan Kha National Park, Chaiyaphum, at pH 7, silt loam soil.

Remarks. Amynthas longicaeca , new species, is easily distinguished from the other two earthworms of the aelianus species group reported from Thailand, namely A. fucosus ( Gates, 1933) and A. siam Blakemore, 2011 , of 3–6 mm body width, while the current new species is about 10 mm in diameter. This new species is quite similar to A. burchardi from Sumatra and A. osmastoni from Andaman Island in body dimensions but differs in having crescent shaped genital markings in the male pore region while A. burchardi has a group of small circular papillae in mid-ventral XVIII and A. osmastoni has genital markings in the spermathecal pore region ( Table 1).

Figures

Fig. 4. External and internal morphology of holotype (CUMZ 3304) of Amynthas longicaeca, new species: A, external ventral view; B, internal dorsal view; C, spermathecae. Dark arrow indicates the connection of the spermathecae and spermathecal pore.

Fig. 11. Photographs showing typical habitat types of the new species: A, B, Amynthas arenulus, new species. A, earthen dyke around paddy field; B, casting. C, D, Amynthas longicaeca, new species. C, dipterocarp forest; D, casting. E, F, Amynthas thakhantho, new species. E, organic gardening; F, tower–like casting.