divergens ( Cognetti, 1905 )

James, Samuel W. & Gamiette, Franciane, 2016, New species of Dichogaster Beddard, 1888 (Clitellata: Benhamiidae) with additional records of earthworms from Guadeloupe (French West Indies), Zootaxa 4178 (3), pp. 391-408 : 401-402

Omodeoscolex divergens ( Cognetti, 1905)

( Figure 4 A–D)

Material examined. All these specimens taken from bromeliad leaf axils. Capesterre, Etang As de Piques, (4) N16°01.410', W61°38.562', 782 m asl, montane forest; Village Bouillante, (5) N 16 07.413'; W 61 44.395', 876m asl, montane cloud forest; Monts Caraibes, (3) N15°N15°58.496', W61°41.263', 629 m asl, montane forest; Trace des crêtes, (1) N16°09.686', W61°43.817', 692 m asl, of montane forest; Matéliane par Sarcelle, (2) N16°06.586', W61°39.967', 945 m asl, high elevation herbaceous vegetation; Grande Découverte, (2) N16°03.567', W61°40.235', 1261 m asl, in bromeliads of high elevation herbaceous vegetation; Trace Mewart, (5) N16°07.169', W61°41.132', 994 m asl, in bromeliads of high elevation herbaceous vegetation; Trace Mewart, (1) N16°08.515', W61°40.631', 577 m asl, wet montane forest; (3) Petit Bourg, Morne a Louis, N16°11.167', W61°44.960', 754 m asl, montane forest.

Description. Dimensions 50–100 mm by 1.5–2 mm at segment xxx, 2 mm at clitellum; body cylindrical throughout, segments 120–130. Pigmentation always red and only on peritoneal surfaces including anterior septa, but not always abundant; some populations strongly colored and others only faintly pink. Setae closely paired throughout; setal formula AA:AB:BC:CD = 3:1:3:1 at x, 4:1:4:1 at xxx; DD> 1/2 circumference throughout.

Prostomium epilobous open, broad; segments without secondary annulations. First dorsal pore 5/6, spermathecal pores on small circular bumps in 6/7/8/ 9 in AB. Ovipores paired equatorial median to A in xiv; male pores in xviii; prostatic pores and penial setae at ends of grooves in A in xvii–xix; grooves straight, not surrounded by raised field. Clitellum xiii–xx, saddle-shaped reaching to B, no other genital markings ( Fig. 4 a, b).

Septa 7/8–12/13 slightly muscular, greatest thickness at 11/12. Alimentary canal with weak flaccid gizzard in vi; esophagus valvular in xvi, intestinal origin xvii; no typhlosole, no caeca or intestinal regional differentiation. Calciferous glands reniform, paired in xiv–xv, composed of longitudinally-oriented lamellae opening to medial lumen; each gland with separate pre-septal duct to esophagus. Holonephridia 2 per segment, pre-intestinal nephridia tubular, intestinal segments nephridia with dense cellular mantle containing oil droplets; placed from CD to mid-dorsal. Vascular system with ventral trunk, single dorsal trunk, these connected by commisural vessels in vi–ix, large latero-esophageal hearts in x–xii. Fan-shaped ovaries composed of long strings, with funnels in xiii; paired spermathecae in vii–ix, variable shape among populations: bulbous duct with sessile small diverticulum and narrower ampulla ( Fig. 4 c); or short duct slightly narrower than ampulla, no diverticulum, ampulla ovate with sperm ( Fig. 4 d); or spermathecae reduced and non-functional. Male sexual system holandric, testes and funnels free in x, xi; small seminal vesicles in ix, xii; tubular prostates with short glands slightly longer than ducts, short delicate ducts, sharply marked from glandular portion; penial setal follicles just median to ducts. Penial setae absent, vestigial or numerous but small, straight, unornamented, monomorphic.

Remarks. Only the Monts Caraibes and Petit Bourg specimens clearly showed functional male organs, but these two populations differed greatly in pigmentation. It is not clear if all the specimens we attribute to O. divergens should be placed in a single species. There is roughly 4-fold variation in body size, two or three levels of pigmentation, asexual lineage(s), a sexual lineage, and variation in spermathecal structure. Overall somatic morphology, disregarding size and pigmentation, is uniform.

Figures

FIGURE 4. Omodeoscolex divergens (Cognetti, 1905). A. Dorsal view, live photo, Vent Souffle population (VSP). B. Ventral view VSP. C. Spermatheca VSP (not to scale). D. Spermathecae, Morne a Louis population.