Parachilota timothyi, Plisko, 2008

Plisko, J. D., 2008, New South African Acanthodrilinae earthworm species, with new data for some earlier known members of the genus Parachilota (Oligochaeta: Acanthodrilidae), African Invertebrates 49 (2), pp. 21-21 : 27-30

Parachilota timothyi sp. n.

Figs 6–9

Etymology: Named after Mr Timothy Liversage, who assisted with collection of the type series.

Diagnosis: Spermathecal pores in intersegmental furrows 7/8 and 8/9. Clitellum saddleshaped on 13,14–1/n17,17. Male pores in 18. Prostatic pores not approximate towards the mid-ventral line, in 17 and 19. Gizzard in 5, well developed. Commencement of intestine in 16. Last pair of lateral hearts in 13. Seminal vesicles paired, in 9 and 11. Spermatheca with unilobate diverticulum attached to basal part of spermathecal duct, extending to joint duct/ampulla and invagination of ampulla.

Description:

External features: Body cylindrical, firm. Colour: In life dorsally violet, ventrally brownish grey; alcohol-preserved dorsally violet, extending violet colouration laterally to c setal lines, with dark tint on preclitellar and few last posterior segments. Colour fading after extended preservation. Dimensions: Holotype 140× 7 mm; clitellate paratypes 120–137× 6–7 mm; juvenile 30–72 mm. Segment number: Holotype 153; clitellate paratypes 163–210; juvenile 109–220. Prostomium: Tanylobous with obvious sutures. Setae: Paired; on postclitellar segments aa: ab: bc: cd = 3.5:1.8:4:2; distance between ab decreasing on 12–17, increasing on 19–27; this characters clearly observed also on juvenile specimens. Dorsal pores: Not observed. Nephridial pores: Not observed on holotype, although on some individuals noted occasionally in postclitellar intersegmental furrows, in c setal lines. Spermathecal pores: Paired; in 7/8 and 8/9, in front of b. Female pores: Paired, in 14 between aa. Clitellum ( Fig. 6 ): Saddle-shaped, whitish yellow, on 13,14–1/n17,17; anterior borders obvious, posterior faint, ventrally extending to b setal lines. Prostatic pores: Paired in 17 and 19, on prominent swellings encircling b setae. Male pores: Paired, in 18, small vertical openings ventrally to b setae. Seminal grooves: Straight or slightly curved. Papillae: Prominent swellings, oval, single or paired, in a setae line, variably on some segments: 8, 10, 16–20, 21, 20–24.

Internal characters: Salivary glands: Do not extend backwards beyond septum 4/5. Gizzard: In 5, well developed, cylindrical, muscular. Septa: 5/6 and 6/7 little thickened; 7/8–10/11 increasing in thickness with 10/11 most thickened; 11/12–15/16 decreasing thickness, becoming less muscular, although strong; some variations in thickness intensity observed, but thickening always obvious in 7/8–15/16. Intestine: Commences abruptly in 16 or in the middle of 16; oesophageal longitudinal ridged valves in 14–15. Lateral hearts: In 9–13, first pair very thin vessel; last pair in 13 much enlarged. Nephridia: Holoic ; thin, elongated coiled loops extend vertically, with no terminal vesicles. Ovaries: Not observed. Testes and male funnels: Ventrally in 10; funnels large, free, iridescent. Vasa deferentia: Not observed. Seminal vesicles: Paired, in 9 and 11; anterior pair small, commencing at septum 9/10 ventrolaterally, little lobulated; posterior pair commencing dorsolaterally at septum 10/11 large, brownish, much lobulated. Spermathecae ( Fig. 7 ): Paired; in 8 and 9; ampulla smooth, 2 mm long and nearly 2 mm wide, with external indentation at link with spermathecal duct; duct 1 mm long; unilobate diverticulum commencing at basal part of spermathecal duct, extending to joint duct/ampulla locates its global ental part in ampulla’s external dent. Iridescent sperm was observed in ental part of diverticulum. Ectal parts of spermathecal ducts enter body wall at 7/8 and 8/9. Prostates ( Fig. 8 ): Paired, in 17 and 19. Prostatic duct commences as thin, soft tube, extending into thicker, muscular, folded, lobulate gland, confined to one segment; prostatic gland sometimes extends backwards, conically pushing septum into space of neighbouring segment. Ectal parts of prostatic ducts enter body wall in 17 and 19. Penial setae ( Fig. 9 ): a and b transferred into penial setae; 5–6 mm long, slender; steam straight, curved at distal end. Variable in shape and size in individuals collected in the same locality. Penial setal retractor muscles: Commence intersegmentally in 17/18 and 19/20.

Holotype: Mpumalanga: NMSA /Olig.02204, 17 km N of Volksrust (27°22'S: 29°53'E), right side at crossroad to Sandspruit , recently burnt grass, moist black soil, ca 25 cm deep between roots of various plants, 5.xii.1995, JDP & T. Liversage.

Paratypes: NMSA / Olig. 03639, 10 cl, and NMSA / Olig. 03640, 6 semi-mature, collected with holotype. KwaZulu-Natal : NMSA / Olig. 02354, Ncandu Nat. Res. (27°53'30"S: 29°42'30"E), ca 1830 m, grassland plateau along Ulumbi R., riverine bush mixed with exotic and indigenous trees, moist, rich soil, between roots of diverse plants, 31.i.1996, 2 cl & 20 in different states of maturity , JDP [specimens collected in close vicinity of P. nkandu sp. n.].

Other material examined: Mpumalanga: NMSA/Olig.01835, 3 juv, 32 km W of Volksrust, on bank of Skulspruit R., under willow tree ( Salix sp. ), marshy, wet soil, 3.xii.1992, JDP & BRS [indigenous microchaetid Tritogenia palusicola Plisko, 1997 , exotic lumbricid Aporrectodea rosea (Savigny, 1826) , Aporrectodea trapezoides (Dugès, 1828) , and megascolecid Amynthas sp. collected in the same sample]. KwaZulu-Natal: Ncandu Nat. Res. grassland plateau around Ulumbi R., at ca 1830 m: NMSA/Olig.02353, 4 cl & 16 juv, below bank of Ulumbi R., in indigenous riverine bush, moist, rich soil, 30.i.1996; NMSA/Olig.02341, 14 cl, grassland plateau, on rocks covered by wet moss, under various plant roots, 29.i.1996; NMSA/Olig.02344, 15 cl & 11 juv, grassland, moist, sandy soil, 30.i.1996; NMSA/Olig.02346, 4 cl + 2 juv, and NMSA/ Olig.02347, 3 juv, river bank, in wet sandy soil, 30.i.1996 [with exotic lumbricids Octolasion lacteum (Örley, 1881) and Dendrodrilus rubidus (Savigny, 1826) ]; NMSA/Olig.02355 & NMSA/Olig.02356, 2 cl, wet sites, grassland near the river, 29.i.1996 [with endemic microchaetid Proandricus bourquini Plisko, 1996 ]. All material collected by JDP.

Comparative material of Parachilota wittebergensis Pickford, 1937 examined: Eastern Cape: SAMC A21616 , Witteberg Mtns, Avoca farm, on bank of stream, damp soil, 1 cl, 3.v.1928, E.G. Pickford .

Distribution: Known from the outskirt of the Drakensberg Escarpment in the northwestern part of KZN, and in Mpumalanga.

Biological notes: The species occurs in grassland and forest soil, on river banks, and near roads. Abundant in Ncandu Nat. Res. grassland plateau around the Ulumbi R., at ca 1830 m in moist soil, and between various plant roots on the river bank, in indigenous riverine bush, and on scattered grassland plateau rocks covered by moist moss watered by flowing water. The new species occurs together with the indigenous acanthodriline Parachilota ncandu sp. n., the microchaetids Proandricus bourquini Plisko, 1996 and Tritogenia palusicola Plisko, 1997 , and with the exotic lumbricids Aporrectodea rosea (Savigny, 1826) , Aporrectodea trapezoides (Dugès, 1828) , Octolasion lacteum (Örley, 1881) , Dendrodrilus rubidus (Savigny, 1826) , and megascolecid Amynthas sp.

Discussion: P. timothyi , having the last pair of lateral hearts in 13 and the intestine commencing in 16, may be related to P. wittebergensis Pickford, 1937 , known from Witteberg Mountains and Mont-aux-Sources, both sites located south of the occurrence of the new species, in the Drakensberg Mountains. The species differ in the shape of the spermathecae, which are bilobate in witteberngensis, attached to anterior face of spermathecal duct, while in timothyi the unilobate diverticulum is at the base of the duct, extending to the junction with the ampulla.

Figures

Figs 6–10. Parachilota species with unilobate diverticulum: (6–9) P. timothyi sp. n., holotype: (6) anterior part of body, ventrally, 40×; (7) spermathecae of segment 8 and 9, 400×: (8) prostates of 17 and 19, 370×; (9) genital setae of 17 (a seta, 9A) and 19 (b seta, 9B), 500×; (10) P. wahlbergi (Michaelsen, 1899), spermathecae, 500×. Abbreviations: A – ampulla, Cl – clitellum, D – spermathecal duct, Pd – prostatic duct, Pg – prostatic gland, PR – prostatic pores of 17 and 19, Udv – unilobate diverticulum.