Pithemera malindangensis, Aspe & James, 2015

Aspe, Nonillon M. & James, Samuel W., 2015, New Polypheretima and Pithemera (Oligochaeta: Megascolecidae) species from the Mt. Malindang Range, Mindanao Island, Philippines, Journal of Natural History 49 (37), pp. 2233-2255 : 2244-2245

Pithemera malindangensis sp. nov.

( Figures 2B and 3B )

Diagnosis

White worm; adult length 91–144 mm; clitellum from xiv through half of xvi; five pairs of spermathecal pores, 4/5–8/9; distance between male pores 0.2 circumference apart; no genital markings; intestinal origin in xiv; prostate glands from xvi–xix.

Etymology

The species is named for Mt. Malindang.

Material examined

Holotype: adult (NMA 4528), Mt. Malindang Range (8.2986°N, 123.6169°E), Barangay Lake Duminagat , municipality of Don Victoriano, Misamis Occidental Province, Mindanao Island, Philippines; 1357 m a.s.l; coll. Nonillon Aspe, Nolan Aspe and J. Adeva, 9–15 October 2003 . Paratypes: three adults (NMA 4547); two adults ( ZRC.ANN.0014); all same collection data as for holotype .

Description

White, clitellum grey–brown. Adult length 91–144 mm (n = six adults); diameter 4 mm at x, 3.5 mm at xx; body cylindrical in cross-section, tail blunt; 118–126 segments. First dorsal pore at 13/14, inconspicuous in most specimens; paired spermathecal pores 4/5/6/7/8/9, inconspicuous; female pores paired in xiv, male pores on paired circular porophores forming mounds in xviii, 0.2 circumference apart, two to four setae between openings. Clitellum annular, extending from xiv through half of xvi. Setae evenly distributed around segmental equators, 58 setae on vii, 30–40 setae on xx; dorsal setal gap absent, ventral gap present. Genital markings lacking.

Septa 5/6/7/8 muscular, 8/9 absent, 9/10–13/14 muscular. Dense tufts of nephridia on anterior faces of 5/6 and 6/7; nephridia of intestinal segments located at septum– body wall junction, mainly on body wall near anterior and posterior faces of septa. Gizzard large, extending from viii to ix; oesophagus with internal lamellar sections extending from xi to xiii; intestinal origin in xiv; caeca from xxii to xxi; typhlosole a simple fold of about one fifth lumen diameter, originating in xxii; intestinal wall lacks longitudinal blood vessels.

Hearts in x–xii, oesophageal. Commissural vessels in vi, vii and ix, lateral; lacking in viii. Supra-oesophageal vessel extending from x to xii; extra oesophageal vessels joining ventral oesophageal wall in x, receiving efferent parieto-oesophageal vessels in xiv.

Ovaries and funnels free in xiii. Spermathecae five pairs in v to ix; duct short, slender; small, spherical to ovate ampulla greater than duct length; diverticulum stalk short, attached ectally to duct, terminating in short, sausage-shaped receptacle. Male sexual system holandric; testes and funnels enclosed in paired ventral sacs in x and xi; seminal vesicles in xi and xii; vasa deferentia slender, free from body wall, those on each side separate until xiv, joining ental end of prostatic ducts; each prostate racemose, broad, multilobed, in xvi–xix; ectal half of duct expands to form muscular spindle; ducts in hairpin loop. Transverse muscle bands present above body wall at 16/17 and 18/19, the latter much larger. Copulatory bursae lacking.

Remarks

Pithemera malindangensis sp. nov. belongs to the Pi. bicincta ( Perrier, 1875) species group of Sims and Easton (1972), which initially comprised two species, Pi. bicincta and Pi. violacea Beddard, 1895 . Michaelsen (1910), Ohfuchi (1957) and Shen and Tsai (2002), however, considered Pi. v iolacea to be a junior synonym of Pi. bicincta . Pithemera bicincta , first collected from Mindoro Island, has the first spermathecal pores in 4/5, and the intestinal caeca are paired and positioned laterally. Pithemera malindangensis is similar to Pi. bicincta in the arrangement and number of spermathecae and septa, the number and locations of hearts, and the length of the caeca, but the former is larger, lacks genital markings, and has the intestinal origin in xvi rather than xv. Other members of the bicincta species group reported from the Philippines (all from Luzon Island except for Pi. duminagati sp. nov. described below) include Pi. rotunda and Pi. philippinensis ( James et al. 2004) ; Pi. duhuani , Pi. fragumae , Pi. ifugaoensis and Pi. triangulata ( Hong and James 2008a) ; and Pi. glandis , Pi. fusiformis and Pi. levii ( Hong and James 2011a) . Pithemera malindangensis sp. nov. and Pi. duminagati sp. nov. are similar to most or all other members of the bicincta group in the origin of the gizzard, number of hearts, and length and location of the caeca, but differ from the others in having the intestinal origin in xvi rather than xv. The Malindang species are also white and lack genital markings. Pithemera malindangensis sp. nov. is larger than Pi. duminagati sp. nov., the male pores are more distant and it has only two pairs of dense tufts of nephridia (on the anterior faces of 5/6/7), whereas the latter has three pairs (on 5/6/7/8; Table 3).

Occurrence

Pithemera malindangensis sp. nov. was the most abundant among the four species, comprising 11.7% of all earthworms collected. It was common in primary and disturbed forests in Barangay Lake Duminagat at elevations of 1479–2027 m a.s.l. The soil it inhabited was covered with thick leaf litter and roots, bryophytes and lichens. We did not observe it on rotten logs.

Figures

Figure 2. Schematic drawings of the external anterio-ventral area of (A) Polypheretima mindanaoensis sp. nov., (B) Pithemera malindangensis sp. nov., (C) Pithemera duminagati sp. nov. and (D) Pithemera donvictorianoi sp. nov. Abbreviations: fp, female pore; cl, clitellum; mp, male pore; gm, genital markings. Scale bars: 5 mm.

Figure 3. Schematic drawings of the internal morphology of (A) Polypheretima mindanaoensis sp. nov., (B) Pithemera malindangensis sp. nov., (C) Pithemera duminagati sp. nov. and (D) Pithemera donvictorianoi sp. nov. Abbreviations: s, spermatheca; n, dense tufts of nephridia; h, heart; p, prostate gland; c, caecum. Scale bars: 5 mm.