Libyodrilus maryae, 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 : 1862-1864

Libyodrilus maryae n. sp.

(figures 6B, 8A, 10D)

Material examined

Type material. Cameroon, just E of Akom II, 2 ‡ 51 ’ N, 10 ‡ 54 ’ E, near Biwoume River , clayey to sandy soil in slough, 12 January 1966, coll. M. W. Clausen (holotype: one clitellate, ZMUC OLI-5 ; paratypes: three clitellates, three aclitellates, ZMUC OLI-6 ) .

External characters (figure 8A)

HOLOTYPE: length 164 mm (variation in two undamaged clitellate paratypes 135–170 mm), maximum diameter 3.6 mm (2.5–3.6), 174 segments, probably regeneration of hind end, last 13 segments small (the two undamaged clitellate adults with 200 and 205 segments). Segments 8–13 tetra- to multi-annulate, annulation in clitellum almost indistinguishable, behind clitellum multi-annulate, gradually becoming less annulated and disappearing posteriad. Prostomium prolobous. Clitellum orange, rest of body without pigment (fixed specimens). Setae uniform. Setal formula: aa: ab: bc: cd ~ 11.7:1.3:8.3:1.0, dd ~ two-thirds of body circumference at segment 10; 8.0:1.0:4.4:1.0, dd ~ two-thirds of body circumference at segment 30. Setae not visible in clitellar region except for penial setae in 17. Clitellum annular, with up to five segments in 14–3/4 18, 18, replaced by genital swelling ventrally in segment 17 (see below).

No dorsal pores. Nephridiopores not discernible.

Spermarial pore unpaired, minute opening m/v in setal zone in 13. Opening surrounded by circular, whitish area (diameter about ab).

Female pores paired, minute openings in segment 15 near 14/15, 1 cd –4 cd dorsal to d.

Male pore unpaired, m/v in 17 in setal zone on small oval swelling covering area between setal lines a or b and posterior two-thirds of segment 17.

Internal characters

First septum 4/5. Septa 4/5–11/12 with thick muscular layer, all succeeding septa thin. Pharynx extending posteriorly to 4/5. Oesophageal gizzards, ventral oesophageal sacs and calciferous glands absent. Intestine commencing in posterior half of 19. Three intestinal gizzards, one in each of segments 23, 24 and 25. Anterior to gizzards thin-walled sections of gut with four pouches (two dorsally and two ventrally) next to septa. Median typhlosole present from segment 20 (one specimen) or 26 (two specimens) becoming gradually less distinct towards hind end (about segment 135 in type). Lateral typhlosoles present in segments 26–35 or 36.

Dorsal blood vessel bifurcating segmentally, but reuniting passing through septa in 13–20, 21 or 22. Vessel traceable to posterior face of 5/6. Supra-oesophageal trunk visible in 6–12, larger in posterior segments than in anterior ones. Hearts in 6–12. Subneural trunk dividing into two extra-oesophageal vessels just in front of 15/16.

Excretory system holonephric.

Holandric. Testes well developed, free, one pair in each of segments 10 and 11. Funnels paired in 10 and 11, large with numerous plications and with white iridescence. Seminal vesicles paired in 11 and 12. Anterior pair restricted to segment 11, posterior one extending to about 19/20. Vasa deferentia entering lateral sides of euprostates approximately 1.2 mm from ectal end.

Euprostates. Two almost regular tubular organs, lying ventro-lateral to the intestine in 18–20. They bend mediad, gradually narrowing before penetrating body wall in 17.

Follicles of penial setae situated just in front of and mediad to euprostates. One seta in each sac. Penial setae (figure 6B) about 1.1 mm long, and with maximum width of 0.07 mm (at base). Shape almost cylindrical, only slowly tapering towards ectal end, ending in a small hook. Setae slightly curved. Growth striation hardly visible.

Spermarium (figure 10D) consisting of dorsal sac with two branches emerging from anterior corners of sac and forming two rings in segment 13: one around oesophagus and one around nerve cord with a tube between them. Under nerve cord spermarium is in connection with spermarial pore through narrow tube. Perioesophageal ring continuing dorsally in tubular sac, extending posteriorly to 16/17 or 17/18. Sac with three pairs of diverticula (in one specimen only two diverticula in right side). Branches of each side meeting latero-ventrally in common tube or ending freely. In type, left branch of first pair merging with perioesophageal ring, in right side ending freely. Second and third pairs connecting with each other in left side, but not with first diverticle or perioesophageal ring. In right side they end freely. Ovisacs situated on posterior face of 13/14, opening into ental part of oviducts in segment 13. Each oviduct overgrowing funnel in 13, and after penetrating 13/14 traverses 14, where it attaches to 14/15, disappearing into body wall at level of female pore in 15. Receptaculum ovorum in connection with perioesophageal ring by short duct near m/v. No ovaries observed (all specimens adult).

Remarks

The spermarium of Libyodrilus maryae n. sp. belongs both to group II and group III because latero-ventral connections are in some cases lacking between some of the diverticula. From all other species in group II and L. bipindiensis in group III (figures 6F, I, J and 5A), L. maryae (figure 6B) differs by the more slender shape of the penial setae. From L. choristoporus in group III it differs by the position of the genital pores (cf. figure 8A and B).

Distribution Only known from the type locality in southern Cameroon, just E of Akom II.

Etymology

The species L. maryae is named after my colleague Mary E. Petersen, who has been an invaluable help in preparing the manuscript.

Libyodrilus mekoensis Clausen, 1965

(figures 6C, D, 8D, 11C)

Libyodrilus mekoensis Clausen, 1965: 279–286 , figures 1–3; Sims, 1987: 364.

Remarks

Libyodrilus mekoensis belongs to spermarial group IV (table 1; figure 11C). The species differs from all other species of Libyodrilus in the shape of the genital field (figure 8D) and penial setae (figure 6C, D).

Relationships with L. violaceus and L. simsi are discussed under L. simsi .

Distribution Known only from the type locality: Meko, 7 ‡ 28 ’ N, 2 ‡ 55 ’ E, Nigeria.