Pheretima barligensis, Hong & James, 2011

Hong, Yong & James, Samuel W., 2011, New earthworm species of the genus Pheretima (Clitellata: Megascolecidae) from Mountain Province, Philippines, Journal of Natural History 45 (29 - 30), pp. 1769-1788 : 1783-1785

Pheretima barligensis sp. nov.

( Figure 6 )

Type material

Holotype: Clitellate (NMA 04378): Philippines, Mountain province, Mt. Amuyao , just below summit at N. slope (17 ◦ 00.81 ′ N, 121 ◦ 07.69 ′ E), 2720 m a.s.l., mossy forest, in soil, 6 April 2001, S. W. James coll. Paratypes: 2 clitellates (NMA 04384): Same data as for holotype .

Other material

Same data as for holotype, 1 semi-clitellate, 1 aclitellate; One clitellate, Philippines, Mountain province, Amuyao Low Ridge (17 ◦ 01.27 ′ N, 121 ◦ 07.00 ′ E), 2233 m a.s.l., lower montane forest, soil, 6 April 2001, A. Castillo coll.

Etymology

The species is named after its type locality near the municipality of Barlig.

Diagnosis

Four pairs of ventral spermathecal pores in 5/6–8/9, 0.16–0.22 circumference apart; copulatory bursae openings 0.19–0.22 circumference apart, openings flanked internally by anterior, posterior circular pads, transverse wedge-shaped penis with groove along the summit of the wedge, intestinal origin in XVI, septa 8/9–9/10 present.

Description

Dark brown dorsal pigment between unpigmented equatorial stripes, stripes visible in clitellum. Dimensions 225–255 mm by 8–9 mm at segment X, 7.5–9 mm at XXX, 8–8.5 mm at clitellum, segments 108–119; body circular in cross-section. Setae numbering 32–38 at VII, 48–53 at XX, 4–6 between male pores, setae slightly more crowded ventrally, setal formula AA:AB:YZ:ZZ = 6:5:6:8 at XIII. Clitellum annular XIV–XVI, setae invisible externally.

First dorsal pores 12/13. Four pairs of ventral spermathecal pores in 5/6–8/9 at 8th setal lines, 0.16–0.22 circumference apart; distance between spermathecal pores 4.5–5.5 mm. Female pore single in XIV; 1.0– 1.5 mm openings of copulatory bursa paired in XVIII at 7th setal lines, 0.19–0.22 circumference apart ventrally; distance between openings 5.0– 5.5 mm. Genital markings lacking.

Septa 5/6–6/7 thin, 7/8 very thin, 8/9 thin, 9/10 present as membrane covering hearts of X, 10/11–13/14 thin. Gizzard in VIII, intestine begins in XVI, mediumsized paired lymph glands from XXVII along dorsal vessel; intestinal caeca simple originating in XXVII, and extending anteriorly about to XXII, finger-shaped sac; typhlosole thick but less than 1/6th intestine diameter from XXVIII. Hearts in X–XIII oesophageal; IX lateral, VIII to gizzard, VII lateral.

Ovaries and funnels in XIII, spermathecae four pairs in VI–IX with nephridia on ducts, cordate ampulla; duct very short, iridescent diverticulum chamber bean seed-shaped, with stalk shorter than ampulla. Male sexual system holandric, testes and funnels in paired ventral sacs in X, XI. Seminal vesicles two pairs in XI, XII with small sub-apical dorsal lobe, prostates in XVII–XVIII, very short stout muscular ducts, entering top centre of copulatory bursae without coelomic glands; copulatory bursa openings flanked posterior, anterior by large circular pads, transverse wedgeshaped penis with groove along the summit of the wedge, facing medially; lateral end of wedge higher, free from bursa roof.

Remarks

Pheretima barligensis sp. nov. belongs to the darnleiensis group in Sims and Easton (1972), which was originally composed of 15 species, all of which were synonymized by Sims and Easton. This species group is defined by having either four or five pairs of spermathecae, the last pair in segment IX, and the optional fifth in segment V. Our examination of several of the species included in the synonymy of P. darnleiensis Fletcher, 1887 suggests that species-level differences have been ignored or discounted against the large number of spermathecae (James, unpublished data). We have discussed this problem at some length in Hong and James (2010), and need not repeat the same arguments in detail. Blakemore et al. (2007) recently expanded the synonymy to include some very large (700 mm) worms from Mt. Kinabalu, Borneo and possibly some of the Pheretima dubia group (three pairs of spermathecae VII–IX). We hold that the synonymy is excessive and buries significant morphological and geographical diversity in an increasingly meaningless concept of P. darnleiensis . In Blakemore et al. (2007) it is stated that the 45–700 mm size range “suggests either high plasticity or too wide synonymy”. We agree, especially with the latter possibility. Sims and Easton (1972) suspected the species of being a peregrine, because it was found on Darnley Island, a small island in the Torres Strait, and outside the known range of Pheretima (Pheretima) . For that reason the variations in size, colouration and other characters were discounted.

Morphologically indistinguishable or similar species have been respectively discovered or differentiated by molecular data ( Chang and Chen 2005, Dominguez et al. 2005; Perez-Losada et al. 2005; King et al. 2008). Of particular interest here is the work of Chang et al. (2007), who showed that size, colouration and genital marking patterns correctly identified genetically distinct lineages within what was previously considered to be a variable species of Amynthas . It is also known that mating in earthworms is size-assortative because each individual hermaphrodite is under selective pressure to choose the largest available mate, resulting in convergence on similarly sized copulating partners ( Michiels et al. 2001; Monroy et al. 2005). In the face of these discoveries, placing morphologically distinguishable taxa of greatly differing sizes into synonymy is probably not useful.

Pheretima barligensis sp. nov. differs from P. darnleiensis in having fewer setae per segment, greater length ( P. darnleiensis 155 mm), and dark brown dorsal pigment, with unpigmented equatorial stripes, stripes visible in clitellum.

We also collected three species of the darnleiensis group from Kalbaryo, Luzon Island (Hong & James, unpublished manuscript), one species from Banaue, Luzon ( Hong and James 2008a), and two species from Balbalasang, Kalinga, Luzon ( Hong and James 2010). Among those, only the Banaue worm also has an intestinal origin in XVI. However, compared to Pheretima barligensis sp. nov., the Banaue species also has fewer setae (26 in VII, 33 in XX), lacks septa 8/9/10, and is less than half the size (98 mm) Table 1.

Figures

Figure 6. Pheretima barligensis sp. nov.: (A) ventral view; (B) spermathecae. Scale bars = 5 mm (A), 2 mm (B).