Okudrilus nyosensis Csuzdi & Sherlock, 2015

Csuzdi, Cs., Sherlock, E., Kouete, M. Talla & Doherty-Bone, T. M., 2015, Four new earthworm species from the highlands of Cameroon with description of a new genus Okudrilus gen. n. (Oligochaeta: Eudrilidae & Acanthodrilidae), African Invertebrates 56 (1), pp. 25-38 : 30-32

Okudrilus nyosensis Csuzdi & Sherlock sp. n.

Figs 7, 8

Etymology: From the type locality, adjacent to Lake Nyos where the holotype was collected.

Diagnosis: L: 82 mm, D: 3 mm. Colour red-violet, paler on ventrum. Head epilobous, setae closely paired. Clitellum annular on ½14–17. Prostatic pores postsetal in 17 a–a, spermathecal pores 12 between a–a, female pores on 14 close to 14/ 15 in d. Gizzard in 6, calciferous glands in 12, chylus-sacs in 10, 11. Testes in 11, vesicles in 12 long running back to 22. Ovo-spermathecal apparatus aired, spermathecal ampulla elongated tube, laterally continues in an ovo-spermathecal duct communicating with the ovarian capsule. The right and left ovarian duct interconnected by a small channel. Prostates without copulatory sacs. Simple penial setae 7 mm in length and 0.02 mm in diameter.

Description:

External characters:

Holotype: Preserved length 82 mm diameter after clitellum 3 mm. Segment number: 168. Colour: Preserved reddish-brown, paler on ventrum. Head: Epilobous, ¾ closed. Dorsal pores: Lacking. Setae: Closely paired, setal ratio aa:ab:bc:cd:dd = 6:1.2:4:1:20. Nephridial pores: Begin on segment 2, somewhat dorsal to setal line d.

Clitellum: Annular on segments ½ 14–17. Prostatic pores: Postsetal on 17 situated on a pair of slightly elevated papilla. The prostatic pores on both sides are connected by a straight seminal groove with small porophores on 18 in setal line a–a. Female pores: Small dots on 14, close to the intersegmental furrow 14/15 just below setal line d. Spermathecal pores: Paired on a small glandular elevation in 12 between setae a–a ( Fig. 7 ). Glandular swellings: One pair on 11 around setae ab connected with the spermathecal pore on both sides by slightly curved grooves.

Internal characters:

Muscular gizzard: Large in 6. Septa : 7/8 slightly thickened, 8/9–11/12 moderately strengthened. Calciferous glands: paired in 12, large curved, chylus-sacs in 10, 11. Dorsal blood vessel: Simple throughout. Hearts: In 9–11, moniliform. Testes and sperm funnels: In 11 enclosed in an oval sperm-reservoir. Seminal vesicles: Long, running alongside the intestine from 12 to 22. Ovo-spermathecal apparatus: Ovaries in 13 enclosed in an ovarian capsule pendant from septum 12/13. The ovarian capsule laterally continuing in an ovarian duct becoming undulating before joining the fertilisation chamber bearing a pendant ovisac. From the fertilisation chamber a straight oviduct leads to the female pore. The ovarian capsule medially communicates with an ovo-spermathecal duct joining laterally the elongated and muscular spermathecal ampulla. The spermathecal ampulla bears ectally a spherical dilatation which continues in a long spermathecal duct opening into the spermathecal pore. The left and right ovospermathecal ducts communicate by a small interconnecting channel ( Fig. 8 ). Prostates: Long simple tubes without bursa copulatrix or bursa propulsoria. Penial setae: Simple, smooth, c. 7 mm long and 0.02mm in diameter.

Holotype: CAMEROON: North-West Region, Lake Nyos 1041 m, 28.v.2012, M. T. Kouete & T. DohertyBone ( NHM 2013.443 )

Remarks: The new species differs from the other two Okudrilus species in the position of the spermathecal pores located in segment 12 (12/ 13 in O. monticolus , 11 in O. sulcatus ) and furthermore in the structure of the ovo-spermathecal apparatus. The habitat where this species was collected was in subsistence agriculture, with a canopy cover estimated ~ 60 and 80 % and largely cOnsisting Of aVOcadO, guaVa and raffia trees. There were also cocoyam, yam and ground nuts.

Figures

Figs 7, 8. Okudrilus nyosensis sp.n.: (7) ventral view of the clitellar region;(8) ovo-spermathecal apparatus. Abbreviations:Fch = fertilization chamber, Fp = female pore, Gsw= genital swelling, Ov = ovarium, Osd = ovo-spermathecal duct, Ovnd = ovarian duct, Ovs = ovisac, Pph = porophore, Pr = prostate pore, Sta = spermathecal ampulla, Stp = spermathecal pore.