Dichogaster caraibensis, James, Samuel W. & Gamiette, Franciane, 2016

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 : 394-395

Dichogaster caraibensis n. sp.

( Figure 2 A–C)

Holotype. MNHN HEL 592 adult, Monts Caraibes trail, Vent Soufflé in rotten tree trunk, Basse Terre, Guadeloupe, N15°58.423', W61°41.131', 540 m asl.

Paratypes. MNHN HEL593, 2 adults, from type locality.

Other material. 1 preserved for DNA extraction, approximately 12 retained alive for culturing.

Etymology. The name caraibensis is derived from the name of the range of low mountains where the type locality is placed.

Description. Dimensions 71–78 mm by 2–2.5 mm at segment x, 2.5–2.8 mm at xxx, 2.5 mm at clitellum; body cylindrical throughout, segments 105–116. Setae all ventral, closely paired throughout; setal formula AA:AB:BC:CD = 4:1:2:1.5 at xxx; DD> ½ circumference. Prostomium epilobous closed; segments with post-setal secondary annulations posterior to clitellum. Blue-green pigmentation throughout, darker anteriorly. First dorsal pore 5/6 (1), 12/13 (2); spermathecal pores in 7/8/ 9 in A. Ovipores equatorial median to A in xiv on ovate papilla; male pores not seen; prostatic pores at ends of grooves in A in xvii–xix; grooves straight, surrounded by raised field with transverse bar papillae on xvii, xix. Clitellum xiii–xx, annular in xiii–xvi, no other genital markings ( Fig. 2 A,B).

Septa 8/9–12/13 very slightly muscular. Alimentary canal with proventriculus in v, two gizzards in vi, vii; esophagus valvular in xvii, intestinal origin xviii, full size in xix; deeply sacculated xix–xxvi; typhlosole a simple fold originating in xxiii, height one quarter lumen diameter, with vertical folds through xxxv, continuous lateral typhlosoles xxv–xxx, typhlosole ends xcvii, lxxxiv. Calciferous glands reniform, paired in xv–xvii, composed of longitudinally-oriented lamellae opening to medial lumen; each gland with separate duct to esophagus; glands xv<xvi<xvii. Micronephridia 10 per segment, pre-intestinal nephridia tubular; intestinal segment nephridia closed sac-shaped with oil droplets; median rows of posterior segments with nephrostomes; median row less mantled and with 3 or 4 lobes; no nephrostomes seen anteriorly; nephridia distributed AB-dorsum. Vascular system with ventral trunk, single dorsal trunk, these connected by commisural vessels in viii, ix, latero-esophageal hearts in x–xii, increasing in size posteriorly. Commissural vessel of vii not seen.

Fan-shaped ovaries composed of long strings, with funnels in xiii; paired spermathecae in viii, ix, each a long undifferentiated tubular axis with slight terminal swelling, small spherical sessile diverticulum ( Fig. 2 C). Male sexual system lacking; very small tubular prostates with very short delicate ducts, sharply marked from narrow tubular glandular portion; penial setal follicles and penial setae very small, vestigial, just median to ducts; yet follicle muscle bands extend nearly to mid-dorsal.

Remarks. Distinctions from global Dichogaster (Dichogaster) are discussed under the previous species. The other Guadeloupe acaecate, male-sterile, blue-green pigmented species is D. athena James, 1996 . Unlike D. caraibensis it has a schizolobous prostomium, 14 nephridia per segment, and lacks spermathecae entirely. To date the former is known only from bromeliad and palm leaf axils in higher elevations ( James 1996 and below). We only located the latter in one place, in a large rotting log where it was abundant. The difference in first dorsal pore location between one specimen and the other two is larger than typically seen within a species in Dichogaster s.l. but otherwise the morphologies match exactly.

Figures

FIGURE 2. Dichogaster caraibensis n. sp. A. Dorsal view, live photo. B. Ventral view, clitellum region. C. Spermatheca.