Libyodrilus choristoporus, Clausen, 2004

Clausen, Martha Weis, 2004, Description of seven new species of Libyodrilus Beddard from Cameroon, with a key to the species of the genus (Oligochaeta: Eudrilidae), Journal of Natural History 38 (15), pp. 1851-1880 : 1855-1856

Libyodrilus choristoporus n. sp.

(figures 2, 8B, 11A)

Material examined

Type material. Cameroon, Bipindihof, Bipindi, 3 ‡ 1 ’ N, 10 ‡ 5 ’ E, coll. G. Zauber (holotype: one clitellate, ZMH V-8508). The specimen was found in the same jar as Libyodrilus bipindiensis n. sp. The state of preservation is bad, the worms being very soft and difficult to handle .

External characters (figure 8B)

HOLOTYPE: length 95 mm, maximum diameter 3.5 mm, 167 segments. Only some weak traces of annulation visible in a few segments behind clitellum. Prostomium prolobous. Clitellum yellow, rest of body without pigment (fixed specimens). Setae uniform. Setal formula: aa: ab: bc: cd ~ 9.2:1.2:6:1, dd ~ two-thirds of body circumference at segment 10; 7.6:1:5.2:1, dd ~ two-thirds of body circumference at segment 30. Clitellum annular, with three segments in segments 1/2 14–1/2 17.

Dorsal pores absent. Nephridiopores not discernible.

Spermarial pores paired, in segment 13, halfway between setal zone and 12/13, and between a and b. Pores surrounded by low elliptical swellings reaching from setal zone to 12/13 within b. Longest axis (parallel to eq) equal to 1/2 aa.

Female pores paired, minute, in setal zone in segment 15 dorsal to d, distance to d about 7 6 cd.

Male pores paired, minute circular openings in segment 17, between setal zone and 17/18 and between a and b. Pores surrounded by low, transversely oval swellings (1/2 aa 6 aa) posterior to setal zone.

Internal characters

First septum 4/5, thin; septa 5/6–11/12 slightly thickened; remaining septa membranous. Pharynx extending back to 4/5. Oesophageal gizzards, calciferous glands and ventral sacs absent. Intestine beginning in segment 19. Three intestinal gizzards, one in each of segments 23–25. Gizzards separated by thin-walled sections of gut, in 24 and 25 with four pouches (two dorsally and two ventrally) next to septa. Median typhlosole present from segment 20. Lateral typhlosole present in 26–31.

Blood vessels almost untraceable. Bifurcation of dorsal vessel only visible in 16–18.

Excretory system holonephric.

Holandric. Testes not visible. Well-developed, very plicated funnels paired in 10 and 11. Paired seminal vesicles in 11 and 12, well developed.

Euprostates (figure 2) tubular, ca 3 mm long with maximum diameter of 1.1 mm. Narrow, twisted tube, about 0.3 mm wide and 2 mm long, leading from each euprostate to opening in 17. Vas deferens disappearing into lateral side of tube near ectal end.

Penial sacs present, but setae lost.

Spermarium (figure 11A) consisting of a median dorsal sac with two branches emerging from anterior corners of sac and embracing oesophagus, uniting to a short tube. Tube dividing above nerve cord and penetrating body wall on sides of nerve cord. Dorsal sac irregular, ca 3-mm-long tube with three diverticula on either side. Diverticula and perioesophageal ring on each side in connection with each other ventrolateral to oesophagus. No ovaries visible. Ovisacs lodged in pockets of anterior surface of joined diverticula where these adhere to perioesophageal ring ventrally. Oviducts (about 1.5 mm) leading to female openings.

Remarks

Libyodrilus choristoporus n. sp. is readily distinguishable from all other species of the genus by the position of the widely separated spermarial pores and male pores (figure 8B). It belongs to spermarial group III (table 1).

Distribution Only known from the type locality in southern Cameroon: Bipindihof, Bipindi.

Etymology

The name L. choristoporus refers to the wide separation between the genital pores.