Pheretima monotheca (James, 2004)

Aspe, Nonillon M. & James, Samuel W., 2017, Pheretimoid earthworms (Clitellata: Megascolecidae) from Mt. Apo, Mindanao Island, Philippines with description of eight new species, Raffles Bulletin of Zoology 65, pp. 357-372 : 364

Pheretima monotheca (James, 2004)

Material examined. two adults ( NMP 4624 ; ZRC. ANN 0075 amputee), Brgy Baracatan , Davao City , Mt. Apo National Park (7°00′04″N, 125°21′55″E), 1,524 m asl, Mindanao Island, Philippines, coll. N. Aspe, A. Solis, D. Flores, R. Librado, 11–14 December 2003 .

Diagnosis. Worm with body dimension 62–81 mm × 2.3–3.7 mm; brown dorsum, lighter ventrum, segmental equators pigmented; single midventral spermathecal pores at 5/6; distance between male pores 0.11–0.14 circumference apart ventrally; intestinal origin in xvii; spermatheca with an elongated, bean-shaped ampulla and a large bulbous, muscular duct expanding ectally; prostates two lobes with one in xvi and the other in xix to xx; penis present.

Description. Brown dorsum, lighter ventrum, equators pigmented. Length 62–81 mm; diameter 2.3–3.7 mm; body cylindrical in cross-section, tail tapering; 96–105 segments. First dorsal pore 12/13. Single midventral spermathecal pore at 5/6. Female pore single in xiv. Openings of copulatory bursae paired in xviii, distance between male openings 0.11–0.14 circumference apart ventrally; 3 setae between openings. Clitellum annular, from xiv to xvi. Setae unevenly distributed around equators in some segments; 35–36 setae on vii, 32–41 setae on xx, dorsal setal gaps present, no ventral gaps. Genital markings lacking.

Septa 4/5–7/8 thin, 10/11–12/13 slightly toughened but thin, 8/9, 9/10 absent. Dense tufts of nephridia on anterior faces of 5/6 and 6/7; nephridia of intestinal segments located mainly on body near septum/body wall junction. Large gizzard in viii–x, esophagus with low vertical lamellae x–xiii. Intestinal origin in xvii, caeca simple originating in xxvii, extending forward to xxv or xxviii. Typhlosole originating in xxvii, simple fold, 1/3 lumen diameter. Intestinal wall with 26 longitudinal blood vessels. Hearts in x to xiii, esophageal; commissural vessels in vi, vii, and ix lateral; those in viii extending to gizzard.

Ovaries and funnels free in xiii. Single spermatheca postseptal in the middle of vi, with nephridia on duct; spermatheca with an elongated, bean-shaped ampulla and a large bulbous, muscular duct expanding ectally, two diverticula attached entally to duct, stalks thin, short, terminating in elongated receptacles. Male sexual system holandric, testes and funnels enclosed in paired sacs in x, xi; seminal vesicles in xi, xii, each with a digitate dorsal lobe; vesicles of xi enclosed in testis sacs; vasa deferentia slender, free from body wall en route to ental end of prostatic ducts; prostates two lobes with one in xvi and the other in xix to xx, racemose; muscular duct entering lateral margin of copulatory bursa from anterior part of the prostate, short, thin duct entering posterior margin of copulatory bursae from posterior part of the prostate. Copulatory bursae ovate in xvii–xix; coelomic surfaces muscular, secretory diverticula lacking; pad present on roof; tapering penis present with sheath entirely within the bursa.

Remarks. Pheretima monotheca , which belongs to the P. urceolata group of Sims & Easton (1972) by the location of its spermathecal pore, is similar to P. (Parapheretima) boaensis ( Aspe & James, 2016) in having a single spermatheca in the middle of vi. However, the latter species is significantly larger (94–133 mm × 3.5–4.5 mm) and possesses secretory diverticula projecting from its copulatory bursae. Other Pheretima species with a single spermatheca are P. ambonensis ( Cognetti, 1913) , P. monoporata (James, 2004) , P. arayatensis ( James & Hong, 2004) , P. vergrandis ( Aspe & James, 2014) , and P. concepcionensis ( Aspe & James, 2014) . These species differ from P. monotheca by having their spermathecal pore at 7/8 except that of P. arayatensis , which has its spermathecal pore at 8/9. Pheretima monotheca was first recorded in Mt. Kitanglad, about 160 km away from Mt. Apo.