Eodriloides thompsoni, Plisko, 2007

Plisko, Jadwiga Danuta, 2007, New species of South African acanthodriline earthworms of the genera Eodriloides and Chilota, with a redescription of Chilota quindecimus (Oligochaeta: Acanthodrilidae), African Invertebrates 48 (2), pp. 33-40 : 34-35

Eodriloides thompsoni sp. n.

Figs 1, 2

Etymology: The name is given in honour of Dr P. Thompson (Ezemvelo KZN Wildlife). Diagnosis: One pair of male pores in 18. Spermathecal pores in 7/8 and 8/ 9 in ventrolateral position.Two pairs of bilobate spermathecae; each spermatheca with two slender diverticula. Seminal vesicles paired, in 9 and 11. Prostatic pores in 17 and 19. Gizzard in 5, large. Last pair of lateral hearts in 13. Intestine begins in 17.

Description:

External features: Body cylindrical. Colour: alcohol-preserved material violet-reddish dorsally extending to the c setal lines, and circularly on the last four posterior segments; ventrally yellowish white. Dimensions: holotype 52× 2.7 mm; paratype 42× 2.8 mm. Segment number: holotype 124; paratype 95. Prostomium: epilobous, open into approx. half of first segment. Setae: widely paired; on postclitellar segments aa> bc, ab<cd, cd<bc. Dorsal pores: not observed. Nephridial pores: observed only on few postclitellar segments in c setal line. Spermathecal pores: two pairs, clearly noticeable in intersegmental furrows 7/8 and 8/9, in front of b setae. Female pores: in 14 in front of b setae. Clitellum : on 13–16; clitellar borders anteriorly and posteriorly distinct. Prostatic pores: ventrolaterally, in segment 17 and 19, respectively, each pore on enlarged ( Fig. 1 ), swollen part of segment. Male pores: in 18, in small openings lateral to b setae. Seminal grooves: curved furrows between prostatic pores. Papillae: prominent on 16, in front of prostatic pores.

Internal characters: Salivary glands: not extending beyond septum 4/5, dorsally touching the anterior part of gizzard. Gizzard: cylindrical, large, somewhat muscular, although soft. Septa: anterior septa not thickened; 11/12–15/16 slightly thickened. Intestine: begins in 17, preceded by enlarged, muscular, folded region of oesophagus in segments 12– 14, followed in segments 15–16 by constricted, much narrower part forming valves. Typhlosole: not present. Lateral hearts: four pairs, with last pair in 13. Nephridia : meganephridia; elongated, thin, without terminal vesicles. Ovaries: not observed. Testes and male funnels: funnels large; first pair medially in segment 10, second pair lateromedially in segment 11; free, iridescent. Vasa deferentia : not observed, probably deeply embedded in body wall. Seminal vesicles: two pairs; anterior pair dorsally in 9, lobulated, commencing from ventral part of septum 9/10; posterior pair commencing from septum 10/11, large, extending into 11. Spermathecae: two pairs, bilobate ( Fig. 2 ); in 8 and 9, respectively; ampulla elongated, folded, with wide duct, at base of which are two slender diverticula, similar in size and appearance. Spermathecal ectal openings in intersegmental furrow 7/8 and 8/9. Iridescent sperm was observed only in lower parts of diverticula. Prostates: two pairs; each prostatic gland tubular, multi-folded, tortuous extending into short, slender prostatic duct; ectal openings in segment 17 and 19, respectively. Each tubular gland together with prostatic duct extends in two segments, anterior pair in 16– 17, posterior in 19–20. Penial setal retractor muscles: not observed.

Holotype: NMSA /Olig.03474. KwaZulu-Natal: Karkloof Nature Reserve (29°16'50.654"S: 30°16'52.420"E), Melmoth farm, hillside rocky grassland, among mole-rat mounds, 9.x.2001, A.J. Armstrong, P. Ngwenya . Paratype: NMSA /Olig.03633, 1 cl collected together with holotype .

Discussion: E. thompsoni being holandric and having nephridia without terminal vesicles agrees with characters proposed by Zicsi (1998) for Eodriloides . The position of the last pair of lateral hearts in segment 13 is distinctive for this species, although it is also known in E. octocordatus recorded from the southern part of the Eastern Cape and the south-eastern Western Cape ( Pickford 1937; Zicsi 1998). However, the start of the intestine in the new species is in segment 17, whereas in E. octocordatus the intestine initiates more posteriorly (18/19–20/21). The two species also differ in the shapes of their spermathecae.

Biological notes and distribution: Two mature specimens were collected at the beginning of spring. The presence of iridescent sperm observed in the male funnels and in the lower part of the spermathecal diverticula in both dissected specimens confirms sexual activity. E. thompsoni has been found together with the indigenous microchaetid Tritogenia lunata Plisko, 1997 and juvenile Proandricus species, and also with introduced megascolecid Amynthas species. This species is known only from Karkloof Nature Reserve, KZN. The collection site has been part of a nature reserve for the past 25 years, under protection by Ezemvelo KZN Wildlife; earlier, it was a private farm for many years. This species is known only from the type locality.

Figures

Figs 1, 2. Eodriloides thompsoni sp. n., holotype: (1) ventral area with prostatic pores, 180×; (2) anterior right spermatheca, 300×. Abbreviations: A – ampulla, B – bilobate diverticulum.