Amynthas elnidoensis, Aspe & Manasan & Manlavi & Patiluna & Sebido & Obusan & Simbahan & James, 2021

Aspe, Nonillon M., Manasan, Rafael Ethan, Manlavi, Albert B., Patiluna, Ma. Lotus E., Sebido, Maria Asela B., Obusan, Marie Christine M., Simbahan, Jessica F. & James, Samuel W., 2021, The earthworm fauna of Palawan, Philippines with description of nineteen new pheretimoid species (Clitellata: Megascolecidae), Journal of Natural History 55 (11 - 12), pp. 733-797 : 780-781

Amynthas elnidoensis sp. nov.

( Figure 18 )

Material examined

Holotype: adult ( WPU-A022 ), Brgy. Pasadena, municipality of El Nido (11.216°N, 119.450° E), 196 m asl, Palawan Province, Philippines, coll. S. James, 27 September 2005 . Paratype: one adult ( WPU-A 023), same collection data as for holotype.

Etymology

The species is named after the municipality of El Nido, Palawan, the type locality .

Diagnosis

Small brown worm with adult length 39–45 mm, diameter 2–2.5 mm; 86–89 segments; one pair of spermathecal pores at 5/6; 79–84 setae on vii, 87–96 setae on xx; no setae between male pores; spermathecal pores 0.16–0.17 circumference apart ventrally; male openings 0.15–0.16 circumference apart ventrally; one pair of round genital markings between male pores anterior of the setal line on xviii; caeca simple, originating in xxvi, extending forward to xxi; prostates large in xvi–xx.

Description

Dark brown, equators pigmented. Length 39–45 mm (n = 2 adults); diameter 2–2.5 mm at x, 2.5–3 mm at xx; body circular in cross section, tail tapering; 86–96 segments. First dorsal pore at 12/13, one pair of spermathecal pores at 5/6, spermathecal pores 1–1.3 mm (0.16–0.17 circumference apart ventrally). Female pore single in xiv, pair of male openings in xviii, distance between openings 1.2–1.5 mm (0.15–0.16 circumference apart ventrally), no setae between openings. Clitellum annular, from xiv to xvi. Setae unevenly distributed around equators in some segments; 79–84 setae on vii, 87–96 setae on xx, dorsal and ventral setal gaps present. One pair of round genital markings between male pores anterior of the setal line on xviii.

Septa 5/6–7/8 and 10/11–13/14 thin, 8/9/10 lacking. Dense tufts of nephridia on anterior faces of 5/6 and 6/7; nephridia in intestinal segments located mainly on body near septum/body wall junction. Large gizzard in viii–x, oesophagus with low vertical lamellae x–xiii, intestinal origin in xiv; caeca simple, originating in xxvi, extending forward to xxi. Hearts in x–xiii, oesophageal; commissural vessels in vi, vii and ix lateral.

Ovaries and funnels free in xiii. Spermathecae paired, postseptal in vi, no nephridia on ducts. Each spermatheca with ovate ampulla; slender, bulbous, muscular duct; single stalked diverticulum attached to the ectal portion of spermatheca; stalk slender, terminating in small ovate receptacle. Male sexual system holandric; testes and funnels enclosed in paired sacs in x, xi; seminal vesicles in x–xii, each with digitate dorsal lobe; vesicles of xi enclosed in testes sac; vasa deferentia slender, free from body wall on way to ental end of prostatic ducts; prostates large in xvi–xx; each prostate a single, dense, racemose mass; short, muscular duct forming U-shape directed towards the body wall on xviii.

Remarks

Amynthas elnidoensis sp. nov. belongs to the Am. minimus group of Sims and Easton (1972), characterised by having a pair of spermathecal pores in 5/6. There were previously 26 species recorded in this group ( Nguyen et al. 2020b), and the new species described here is the 27th. Amynthas elnidoensis sp. nov. is the first member of this group recorded in the Philippines. Among the members of the group, Am. elnidoensis sp. nov. is similar to Am. limellulus Chen, 1946 , Am. limellus Gates, 1935 , Am. mutus Chen, 1938 , Am. wui Chen, 1935 , Am. lompobatangensis Michaelsen, 1899 and Am. nugalis Gates, 1931 in size, in having no pre-clitellar genital markings and in having post-clitellar genital markings. However, Am. limellulus has 10 setae between male pores,has its genital markings on xvii,has its prostates on xvi–xxii, and has short caeca (xxvii–xxv); Am. limellus has fewer setae on vii (44–49), has 14–18 setae between male pores, has its genital markings on xvi and xvii, has its prostates on xvii–xiii and has its caeca originating from xxvii and extending to xiii; Am. mutus has 12 setae between male pores,has its genital markings on xix and has short caeca (xvii–xxv); Am.wui has fewer setae on vii (58),has 8 setae between male pores, has its genital markings on vii, has its prostates on xvii–xix and has short caeca (xvii–xxv); Am. lompobatangensis has 10 setae between male pores, has its genital markings on xvii and xix,and has its caeca originating from xxiv extending to xxiii ( Bantaowong et al. 2015); and Am. nugalis has 2 setae between male pores, has its prostates on xvii–xix and has short caeca (xvii–xxv). Amynthas longiprostaticus Nguyen et al. 2020b , Am. minimus Horst 1893 , Am. conchipapillatus Qiu and Sun, 2010 in Sun et al. 2010, Am. funginus Chen, 1938 , Am. papilio Gates, 1930 , Am. zyosiae Chen, 1933 , Am. infantiloides Thai, 1984 and Am. ovaliporophorata Do et al. 1995 are also relatively similar to Am.elnidoensis sp.nov. in size; however, Am. minimus , Am. conchipapillatus and Am. zyosiae have no genital markings, while Am. longiprostaticus , Am. funginus , Am. papilio , Am. infantiloides and Am. ovipapillatus have pre-clitellar genital markings and have different post-clitellar genital marking patterns.Also,aside from the fact that all other species have setae between male pores, they differ from Am. elnidoensis sp. nov. in the size of prostate glands and in the length of caeca.

Figures

Figure 18. Amynthas elnidoensis sp. nov. (a) External ventral view. (b) Internal dorsal view. (c) Spermathecae. Abbreviations: c, caecum; fp, female pores; mp, male pores; p, prostate gland; s, spermathecae; sp, spermathecal pores; sv, seminal vesicles.