Pheretima longigula, 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 : 423-424

Pheretima longigula n. sp.

( Figs 2 D, 6C, Table 2)

Material examined. Holotype: adult (NMA 4511) Brgy Lake Duminagat, municipality of Don Victoriano, Misamis Occidental Province, Mt. Malindang Range (8º17'55"N, 123º37'01"E), 1500 m asl., Mindanao Island, Philippines, coll. Nonillon Aspe, Nolan Aspe and J. Adeva, Oct. 9–15, 2003. Paratypes: three adults (NMA 4535); two adults ( ZRC.ANN.0019), same collection data as for holotype.

Etymology. The species name is derived from the Latin 'longus' (long) and 'gula' (throat), referring to the long esophagus.

Diagnosis. Slender worm reaching 139–186 mm in adult length; red-brown dorsally; one pair of spermathecal pores at 7/8; two pairs of seminal vesicles extending from xi to xiv; slender esophagus; intestine begins in xxi; penes with sheath; bilobed copulatory bursae in xvii to xviii; prostates posterior to copulatory bursae in xix, xx.

Description. Animals in life with red-brown dorsum; equators pigmented. Length 139–186 mm (n= 6 adults); diameter 3.5–4.0 mm at x, 3.8–4.5 mm at xx; body cylindrical in cross-section; 99–110 segments. First dorsal pore at 12/13; pair of crescent shaped spermathecal pores, concave edge of pores anterior to 7/8, 0.24–0.27 circumference apart ventrally; female pore single in xiv; openings of copulatory bursae paired in xviii, 0.17–0.21 circumference apart ventrally, 0–4 setae between openings. Clitellum annular, extending from xiv to xvi. Setae unevenly distributed, 28–47 setae on vii, 27–51 setae on xx, no dorsal or ventral gaps.

Septa 5/6–7/8 and 10/11–13/14 muscular, 8/9/10 absent. Dense tufts of nephridia on anterior faces of 5/6 and 6/ 7; nephridia of intestinal segments located mainly on septa, rather few and very small. Anterior internal organs all elongate; large gizzard extending from viii to x, esophagus has chevron-patterned lamellae from x to xi, low vertical lamellae from xii to xiii; esophagus long, slender, extending from 15/16 to xix; intestine originates in xxi; caeca originate in xxvii, extend forward to xxii, simple with smooth ventral margin; typhlosole originates gradually from xxxiii, simple fold, 1/3 lumen diameter; intestinal wall with 32–36 longitudinal blood vessels.

Hearts in x to xiii, esophageal; commissural vessels vi, vii, and ix lateral; those in viii extend to gizzard; supraesophageal vessel from x to xv; extra-esophageal vessels join ventral esophageal wall in x, receive efferent parietoesophageal vessels in xiii and xiv.

Ovaries and funnels free in xiii; spermathecae paired, preseptal in vii, with nephridia on ducts; ampulla ovate, spermathecal ducts bulbous, muscular, expanding ectally, with three large ridges on internal posterior side, parallel to one another and duct axis; stalked diverticulum attached to duct near ampulla, terminating in short ovate to lanceolate receptacle; stalk short, curved. Spermatophores lenticular to spherical, with short, thin tail curved back onto body of spermatophore. One individual has a misplaced small spermatheca at intersegment 8/9 on the right side of the body wall. Male sexual system holandric; testes and funnels enclosed in paired ventral sacs in x and xi; seminal vesicles in xi–xii and xii –xiv; vasa deferentia slender, free from body wall en route to ental end of prostatic ducts, traveling along medial surface of copulatory bursae; each prostate racemose in xix to xx, muscular duct entering medial posterior face of copulatory bursa; copulatory bursae bilobed, elongate in xvii and xviii, anterior to the prostates. Coelomic surface of copulatory bursa muscular, secretory diverticula lacking; bursae have glandular mass with long, arched pad directed towards opening; posterior portion containing long, nearly cylindrical penis with circular sheath entirely within both lobes of the bursa.

Remarks. Pheretima longigula n. sp. belongs to the P. montana group of Sims & Easton (1972), characterized by having penis sheaths, which the P. sangirensis group lacks. The Pheretima montana group once comprised seven species, but Blakemore's (2007) review of the group concluded that all but two of these species, P. hahli Ude, 1905 and P. vitiensis Beddard, 1892 , are synonymous to P. montana . The only Philippine species detected so far in the montana group, P. longigula is longer than P. montana (length= 70–135 mm) although P. montana is thicker (5 mm diameter). The spermathecal pores are more widely spaced in P. montana (0.5 circumference apart) and the spermathecal duct is longer and more slender compared to that of P. longigula . Pheretima longigula differs from P. hahli and P. vitiensis in the origin of the intestine (xv in P. hahli and P. vitiensis ), the size of the gizzard (viii–ix in P. hahli ), the length of the prostate (xvii–xix in P. hahli and P. vitiensis ), the origin of the caeca (xxvi in P. hahli and P. vitiensis ), and color (yellow brown in P. hahli and P. vitiensis ). Pheretima vitiensis is metandric according to Beddard (1892), but Michaelsen (1900) apparently found differently in placing this species in synonymy with P. montana . Most Pheretima species in the Philippines have the intestine originating in xv or xvi, and P. l o ng i gu l a is unique in having the intestinal origin in xxi, with a correspondingly long esophagus. This species is also unique in the shape of the copulatory bursae and their position relative to the prostate glands, and in having the typhlosole originating in xxxiii, whereas in most other species, it originates in xxvii.

Occurrence. Pheretima longigula was uncommon (2.1% of total specimens), occurring at high elevations (1479–2027 m) in primary and disturbed forest in Brgy Lake Duminagat (Table 1).

Figures

FIGURE 2. Photographs of living Pheretima worms in dorsal view, showing coloration. (A) P. maculodorsalis n. sp.; (B) P. tigris n. sp.; (C) P. immanis n. sp.; (D) P. longigula n. sp.; (E) P. malindangensis n. sp. Scale bars: A – D, 5 cm; E, 3 cm.