Parachilota ncandu, 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 : 25-27

Parachilota ncandu sp. n.

Fig. 5

Etymology: Named after the type locality Ncandu Nature Reserve.

Diagnosis: Spermathecal pores in intersegmental furrows 7/8 and 8/9. Clitellum saddleshaped on 13,1/n13–1/n17,17. Prostatic pores not approximate towards the mid-ventral line, in 17 and 19. Male pores in 18. Gizzard in 5, developed moderatelly. Last pair of lateral hearts in 12. Commencement of intestine in 17. Spermathecae with duct curved at its middle part, and with unilobate diverticulum attached dorsally to spermathecal duct between its bowed part and link with ampulla.

Description:

External features: Body cylindrical; preserved material slightly softened and extended. Colour:Alcohol-preserved specimens yellowish brown or yellowish grey, with irregular, small patches of pigmentation. Dimensions: holotype 52× 2 mm; paratypes 38–55× 2–2.5 mm. Segment number: Holotype 112; paratypes 117–125. Prostomium: Epilobous; tongue open or with small transverse furrow in line with anterior edge of first segment. Setae: Distantly paired; on postclitellar segments aa<bc; ab <cd; 2 ab nearly equal to aa. Dorsal pores: Not observed. Nephridial pores: Not observed. Spermathecal pores: Paired; in intersegmental furrows 7/8 and 8/9, in front of b, with small swellings around. Female pores: Externally not observed. Clitellum: Whitish yellow, or orange, on 13, 1/n13–1/n17,17; saddle-shaped, broaden laterally to b or a setal lines; on some individuals clitellar tissues widen to nearly median line, although not encircling whole body; anterior and posterior clitellar borders obvious; ventral edges faint or evident, depending on individual state maturity. Prostatic pores: Paired, in 17 and 19, with small swellings encircling pores extending to b setae, occasionally widen to a setae. Male pores: Paired, in 18, small openings below b setae. Seminal grooves: Slightly curved. Papillae: Minute, single or paired, oval depressions on 16 and 17.

Internal characters: Salivary glands: Not extending backwards beyond septum 4/5. Gizzard: In 5, well developed; variations in gizzard muscular strength observed, what probably depends on individual maturity. Septa: All septa very delicate, thin; however in some mature individuals septa 6/7–10/11 slightly thicker than anterior; septum 16/17 extremely thin. Intestine: Commences in 17; preceded by oesophageal folds in segments 13–15; thin valve in 16 or only in part of 16. Lateral hearts: Last pair in 12. Nephridia: Holoic ; thin, elongated coiled loops extending vertically; with no terminal vesicles. Ovaries: In 13, bushy, moderate, ventrally. Testes and male funnels: Ventrally in 10; male funnels large, iridescent; clotted sperm attached to lateral parts of funnels observed in few specimens. Vasa deferentia: Not observed due to thin body wall. Seminal vesicles: 2 pairs; in 9 and 11; anterior pair commencing at septum 9/10, oval sacs; posterior pair commencing at septum 10/11 and forming 3–5 folded sacs extends dorsolaterally in 11. Spermathecae ( Fig. 5 ): Paired; in 8 and 9; ampulla globular, 1.3 mm long; duct 1 mm long, curved at its middle part; unilobate diverticulum attached dorsally to spermathecal duct between its bowed part and connection with ampulla; chambered. In some mature individuals sperm fill only basal region of diverticulum. In others, sperm was observed in diverticulum and in small parts of duct, but not in ampulla. Ectal parts of spermathecal ducts enter body wall at 7/8 and 8/9. Prostates: 2 pairs; in 17 and 19. Prostatic glands of anterior pair extend backwards by pushing conically septum 17/18 into segment 18; prostatic duct, slightly coiled, remains in ventral part of segment 17. Prostatic glands of posterior pair, extend through segments 19–20, 21,22; prostatic ducts much thinner than prostatic glands, slightly coiled dorsolaterally, confined to only lateral part of segment 19. Ectal parts of prostatic ducts enter body wall in 17 and 19. Both prostatic glands may be observed externally through translucent body wall. Penial setae: ab of 17 and 19 transferred into penial setae; both similar, not ornamented, curved at their middle parts, with ectal end bent in opposite direction of seta curvature. Penial setal retractor muscles: Commence near septa 17/18 and 19/20.

Holotype: KwaZulu-Natal: NMSA /Olig.02364, Ncandu Nat. Res. (27°53'30"S: 29°42'30"E), ca 1830 m, grassland plateau above Ulumbi R., under moist moss covering large rocks, 29.i.1996, JDP.

Paratypes: NMSA /Olig.03665, 13 in different states of maturity collected with holotype . NMSA /Olig.02345, 5 semi-mature, in wet, sandy soil, 30.i.1996 . NMSA/Olig.02361, 16 in various states of maturity, collected between roots of diverse plants on bank of Ulumbi R., 31.i.1996 (associated with Parachilota timothyi sp. n.). All sites close to locus typicus , JDP.

Other material examined: NMSA /Olig.02342, 8 cl ; NMSA/Olig.2358, 2 cl; NMSA/Olig.02359, 9 cl; NMSA / Olig.02360, 19 in different states of maturity.All found in area surrounding the type locality, in moist sandy soil, between or under various plant roots, in grassland, and on moist rocks with overspilling water, 29.i.1996. All material collected by JDP.

The species grouped by Pickford (1937) in the P. erythrocephalus species-group that was suspected to be similar to P. ncandu were also studied, but found to be different: KwaZulu-Natal: NMSA/Olig.00272 (paratype of P. warreni (Michaelsen, 1913)) , SAMC A21620 (paratype of P. nanus Pickford, 1937 ). Western Cape: SAMC A21594 (paratype of P. erythrocephalus Pickford, 1937 ), SAMC A21584 (paratype of P. bainellus Pickford, 1937 ).

Distribution: Known from the type locality and its neighbourhood, in the Drakensberg Moutains in north-western KZN.

Biological notes: The Ncandu Nat. Res. , earlier known as Incandu Forest Reserve and recently placed under the protection of Ezemvelo KZN Wildlife, is situated on the border of KZN and the Orange Free State. It extends to the Drakensberg northern escarpment, south-west of Newcastle (27°42'S: 29°59'E). The area where the species was abundant extends over the indigenous grassland plateau along the Ulumbi R. at 1830 m above sea level. A large part of the plateau covered by indigenous grassland extends below the river with several small pockets of indigenous bushes, and continues on the other side of the river. P. ncandu was found in grassland moist soil, on the river bank, under stones, and under mosses covering large rocks with flowing surface water. A large species population at different states of development occurred in the grassland and forested areas. Iridescence observed in male funnels and in spermathecal diverticula suggests a summer phase of sexual activity. P. ncandu was collected together with P. timothyi sp. n. and the microchaetid Proandricus bourquini Plisko, 1996 .

Discussion: The commencement of the intestine in segment 17 and the location of the lateral heart in 12, features observed in P. ncandu and P. erythrocephalus Pickford, 1937 , might suggest species relationships. However, the shape of the spermathecal diverticulum and penial setae differ substantially in both species, and a relationship between these two species cannot be confirmed. Considering the geographical distance separating the species, it may rather be suspected that these characters have evolved independently, with parallel differentiation of the spermathecal diverticulum and penial setae. The species accredited by Pickford (1937) to the P. erythrocephalus species-group, P. traegardhi (Michaelsen, 1907) , P. warreni (Michaelsen, 1913) , and P. nanus Pickford, 1937 , known from KZN differ from P. ncandu in the specificity of the spermathecal diverticulum and also in other features. P. bainellus , P. ruficeps and P. adolphus , described by Pickford (1937) and placed in the erythrocephalus species-group, are recorded from the Western Cape and differ in the complexity of their morphological characters.

Figures

Figs 4, 5. (4) Parachilota hottentotianus Pickford, 1937, prostatic glands, 500×; (5) P. ncandu sp. n., holotype, spermatheca of segment 9, 400×. Abbreviations: A – ampulla, D – spermathecal duct, UDv – unilobate diverticulum.