Pheretima potonganensis, Aspe, Nonillon M. & James, Samuel W., 2014

Aspe, Nonillon M. & James, Samuel W., 2014, New species of Pheretima (Oligochaeta: Megascolecidae) from the Mt. Malindang Range, Mindanao Island, Philippines, Zootaxa 3881 (5), pp. 401-439 : 428-429

Pheretima potonganensis n. sp.

( Fig. 7 D, Table 3 )

Material examined. Holotype: (NMA 4526) Brgy Small Potongan, municipality of Concepcion, Misamis Occidental Province, Mt. Malindang Range (8º24'04"N, 123º36'47"E), 900 m asl., Mindanao Island, Philippines, coll. Nonillon Aspe, Nolan Aspe, M. Lluch, and J. Adeva, Feb. 18–25, 2004. Paratypes: three adults (NMA 4545), same collection data as for holotype. Other material: 12 adults ( ZRC.ANN.0027), Brgy Sibucal, Oroquieta City, Misamis Occidental Province, Mt. Malindang Range (8º19'31"N, 123º38'02"E), 991 m asl., Mindanao Island, Philippines, coll. Nonillon Aspe, Nolan Aspe, M. Lluch, and J. Adeva, Feb. 18–25, 2004.

Etymology. The species is named after Brgy Small Potongan, the type locality.

Diagnosis. Brown worms reaching 63–89 mm in adult length; 4 pairs of spermathecal pores from 5/6 to 8/9; first dorsal pore at 12/13; no dorsal setal gap, ventral setal gap present; septa all present from 5/6 to 13/14; intestinal origin in xiv; prostates from xvii to xix; caeca from xxvii to xx.

Description. In living animals, dorsum purple-brown, darker anteriorly; ventral side slightly pigmented anteriorly; equators pigmented; clitellum gray. Length 63–89 mm (n= 16 adults); diameter 4 mm at x, 4 mm at xx; body cylindrical in cross-section; 69–96 segments. First dorsal pore at 12/13; inconspicuous spermathecal pores paired at 5/6/7/8/9; female pore single in xiv; openings of copulatory bursae paired in xviii, white transverse slits, 0.17 circumference apart ventrally, 4 setae between openings. Five annuli per segment in ix–xiii. Clitellum brown, annular, extending from xiv to xvi. Setae on ventrum more closely spaced than those on dorsum, 32–34 setae on vii, 28–44 setae on xx, dorsal gap absent, ventral gap present.

Septa 5/6–13/14 thin, but 13/14 slightly muscular. Dense tufts of nephridia on anterior faces of 5/6 and 6/7; nephridia of intestinal segments located mainly on body wall at anterior and posterior faces of septa, at septum/ body wall junction. Large gizzard in ix to x; esophagus with chevron-patterned lamellae extends from xi to xiii; intestine originates in xiv; caeca originate in xxvii, extend forward to xx, simple, with smooth ventral margin; typhlosole rudimentary; intestinal wall with 26 longitudinal blood vessels.

Hearts in x to xiii, esophageal; commissural vessels in vi, vii, and ix lateral, those in viii extend to gizzard; supra-esophageal vessels in x to xiii; extra-esophageal vessels join ventral esophageal wall in x, receive efferent parieto-esophageal vessels in xiii.

Ovaries and funnels free in xiii, ovisacs lacking; spermathecae paired from vi to ix, with many nephridia on ducts; each spermatheca with ovate to quadrangular ampulla, short non-muscular duct, stalked diverticulum attached to duct near body wall, terminating in short ovate receptacle; stalk almost as long as ampulla. Male sexual system holandric; testes and funnels enclosed in midventral sac in x, paired sacs in xi; seminal vesicles in xi and xii, each with short dorsal lobe; vasa deferentia slender, free from body wall en route to ental end of prostatic ducts; prostates from xvii to xix; each racemose, bilobed, wrapped around copulatory bursa in xviii–xix; short, muscular duct enters apex of copulatory bursa in xviii. Copulatory bursae in xviii to xix. Coelomic surface of copulatory bursae muscular, secretory diverticula lacking; bursae low, circular domes; penis an irregular lump with terminal crease, extending from bursa roof; one horizontally directed pad anterior and the other posterior to opening in each bursa; an angular lateral projection between them may be a third pad.

Remarks. Pheretima potonganensis n. sp. belongs to the P. darnleiensis group of Sims & Easton (1972). It differs from P. darnleiensis in the location of the first dorsal pore, male pore spacing, the number of setae between the male pores, the presence of ventral gaps, the presence of a septum in 8/9, and the origin of the intestine ( Table 3 ). It also differs markedly from Perichaeta belli and P. benguetensis , which Sims & Eastion (1972) synonymized with P. darnleiensis , in coloration and pigmentation pattern and in the extent of caeca, among other characters.

Individuals of P. potonganensis are smaller than those of P. adevai n. sp. and P. lluchi n. sp., and unlike the latter two species, septa are present from 5/6 to 13/14 ( Table 3 ). Pheretima potonganensis also differs in having ventral setal gaps and in the size of the prostate glands, and the caeca are markedly longer than in P. adevai n. sp. and P. lluchi , extending 8 segment lengths from xxvii to xx. Pheretima potonganensis differs from P. lluchi also in the location of the first dorsal pore. Pheretima potonganensis is similar to P. tabukensis from Kalinga, Luzon in the distance between male pores relative to body size, and both have septa from 5/6 to 13/14, but these species differ in the number of setae in vii (19–20 in P. tabukensis ), the location of the first dorsal pore (11/ 12 in P. tabukensis ), the origin of the intestine (xv in P. tabukensis ), and the lengths of the prostates and caeca (xvii–xviii and xxvii–xxv, respectively, in P. tabukensis ) ( Hong & James 2010).

We observed numerous small, round outgrowths attached on the body wall inside some specimens of P. potonganensis . These occurred in different body regions, but were concentrated mostly in the spermathecal region. We speculate that these are some type of parasitic cysts inside the earthworms, but this remains to be investigated.

Occurrence. Pheretima potonganensis was the second-most abundant species after P. adevai , comprising 11.2% of all individuals found on plots. It was also relatively widespread across Mt. Malindang, occurring in disturbed forest at elevations of 238–1662 m, though we did not find it in primary forest at higher elevations. It occurred both in the soil and above ground on substrates such as rotten logs (Table 1).

Figures

FIGURE 7. (A) Diagrammatic ventral view of polythecal Pheretima adevai, showing the spermathecal pores (sp), clitellum (cl), and male pores (m). (B – D) Schematic drawings of the internal morphology of Philippine Pheretima species, in dorsal view: (B) P. a de v ai n. sp.; (C) P. lluchi n. sp.; (D) P. potonganensis n. sp. Abbreviations: s, spermatheca; h, heart; p, prostate gland; cb, copulatory bursa; c, caecum. Scale bars: B – D: 5 mm.