Proandricus amphius, Plisko, 2003

Plisko, Jadwiga Danuta, 2003, Eleven new South African earthworms (Oligochaeta: Microchaetidae) with new information on some known species, and an inventory of the microchaetids of KwaZulu-Natal, African Invertebrates 44 (2), pp. 279-325 : 297-299

Proandricus amphius sp. n.

( Fig. 9 )

Etymology: Gr. amphi = around, on both sides. Refers to the clitellum encircling the segments.

Material examined: KwaZulu­Natal: Holotype NMSA/Olig.03620 Drakensberg, section of Giant’s Castle Game Reserve, Injasuthi (29º06'51"S: 29º26'34"E) opposite camp, hillside at ca. 1540 m, at south­facing slope, wooded grassland at edge of dry drainage in Protea savannah, 2–10 cm below surface among roots of medium­tall Themeda grass, 14 June 2002, AJA. Paratypes: NMSA/Olig.03621, 9 cl; NMSA/Olig.03627, 10 juv. All collected with holotype.

Description based on holotype and paratypes.

External characters:

General: body cylindrical, compact. Colour: in life, and preserved in alcohol, whitishgrey, not pigmented. Dimensions: preserved and slightly contracted holotype 66 mm long, 4 mm wide at 10, 5 mm at tubercula pubertatis; clitellate paratypes 55–67 mm long. Segment number: holotype 120, paratypes 126–131. Prostomium: prolobous, small. Segmentation: secondary annulation present on preclitellar segments; 1 and 2 simple, with irregular longitudinal grooves; 3 simple; 4–9 with two simple ringlets similar in size and appearance; 10 and 11 simple, longer than anterior ringlets; clitellar simple, similar in size, postclitellar simple, shorter than clitellar. Setae: minute, closely paired in regular rows; preclitellarly ab = cd, aa> bc, at posterior end aa = bc. Nephridial pores: conspicuous, below cd setal lines. Female pores: paired, in anterior part of 14, laterally, slightly below cd setae. Male pores: in 17, in tubercula pubertatis area between ab and cd setae. Spermathecal pores: externally not observed. However, during dissection it was observed that ectal parts of first spermathecal pair were entering into thick body wall near furrow located between ringlets of segment 9. Pores were not noted. Ectal parts of second pair located in 10, although also deeply embedded in wall tissues, were extended into intersegmental furrow 10/11.

Clitellar region ( Fig. 9 ): Clitellum: on holotype and mature paratypes segmented, white, encircling segments 1/n11,12–20,1/n21, leaving uncovered by clitellar tissues only area of tubercula pubertatis and some small ventral parts of segment 12 in area of ab setae; anterior border not well marked, with clitellar tissues extending only partly dorsally on 11; posterior border at intersegmental furrow 20/21, on some paratypes extending partially on 21. On less developed paratypes clitellar tissues ventrally were much thinner than those of mature individuals. Tubercula pubertatis: well developed elongated strips, not covered by clitellar tissues, on 1/n16–1/n20, between cd and ab setae, with shallow grooves separating each strip from clitellar tissues. Papillae: prominent, sucker­like swellings, paired, on 16 around ab setae ( Fig. 9 ); both papillae associated with genital glands. On one paratype papillae are displaced: right one on segment 16, left one on 17 .

Internal characters:

Septa: 4/5 5/6 thickened moderately, elastic, strong; 6/7 not thickened, thin; 7/8 most thickened, 8/9 thickened less than 7/8; other septa thin, firm. Gizzard: globular, muscular, in 7. Calciferous glands: in 9, small, globular, distinctly separated dorsally and ventrally. Intestine: commences in 13, in following segments developing into folded tube; in 21– 27 dorsally covered by irregularly twisted folds. Typhlosole: commences in 21 or 22, terminates in holotype in 53. Dorsal blood vessel: 5–7 thin, double, close; 8 double, separated; 9 enlarged, double, cordiform; in 10 and following segments enlarged and simple; simple when crossing septa. Paired dorsoventral vessels: 5–8 thin vessels, 9– 11 enlarged, moniliform. Nephridia: meganephridia ; coiled loops with extended Vshaped caeca. Spermiductal funnels: proandric arrangement; one pair of large, iridescent funnels, enclosed in sacs closely connected posteriorly at septum of 10 with seminal sacs. Vasa deferentia : distinct single ducts commencing at lateral parts of spermiductal funnels, run backwards at each side of the body to posterior parts of 16, entering body wall in anterior part of 17. Connections with male pores are covered by body wall, however, externally marked male pores indicate on their termination in 17. Seminal vesicles: one pair of composite sacs, commencing at septum 10/11 extending into 11, where pushing, although not interrupting septum 11/12, occupies space of 12. Sacs, variable in shape and size, consist of granulated lobes connected with spermiductal funnels at their base. Spermathecae: in 9 and 10; anterior pair differ in size and shape from posterior pair, being elongated duct, with no sperm, and entering body wall in 9; it is however not clear if ducts penetrate whole thickness of the body tissues, or ducts are ending blindly. Large, elongated­oval, iridescent ampullae with long, curved ducts of posterior pair enter intersegmental furrow 10/11. In all dissected mature specimens posterior pair was full of sperm, although anterior pair was always empty. Ovaries: not observed. Genital glands: one pair in 16 associated with papillae; both glands flat, twice­ or three­folded, moderate in size.

Biological notes: The species was collected at Injasuthi, an area of the Giant’s Castle Game Reserve, in the Drakensberg foothills, protected by KZN Wildlife, where there are large open areas of indigenous grassland and patches of indigenous bushes. Mature and juvenile specimens were found in winter, at an altitude over 1500 m. Iridescent posterior spermathecae and spermiductal funnels observed in mature individuals indicate maturity and sexual activity in late summer, extended into late autumn and possibly also in early winter. The species was found in association with an indigenous acanthodrilid of the genus Udeina .

Discussion: The location of spermathecae in segments 9 and 10 suggest assignation to the lesothoensis species­group. The species is similar to adami sp. n. having clitellum encircling body, although in the last species encircling is not complete. However the species differ in the location of the pores of the anterior spermathecae. Similar to sani , having anterior pair of spermathecae in segment 9 with ectal parts entering intrasegmental body wall, a condition rarely observed in microchaetids. In the other species of the lesothoensis species­group, the spermathecal pores are in intersegmental furrows 9/10 and 10/11 ( adami sp. n., lesothoensis and bourquini ) or only in 10/11 ( pajori ). P. amphius differs from sani by having the clitellum encircling the clitellar segments dorsally and ventrally, with the exception of tubercula pubertatis and small anterior portion of segment 12 in the area of ab setae and papillae. The lack of sperm in anterior spermathecae and entirely filled posterior pair observed in amphius suggests that during copulation the sperm may not enter anterior spermathecae. It is possible that ectal parts of the first spermathecal pair are not completely developed.

Distribution: The species is known only from the type locality ( Fig. 7 ), in an area where some other species of the lesothoensis species­group are known to occur.

Figures

Fig. 9. Proandricus amphius sp. n., holotype, ventral view with clitellum, tubercula pubertatis and papillae. [C = clitellum, T = tuberculum pubertatis, P = papilla of segment 16].

Fig. 7. The distribution of Proandricus species in KZN. 1 = adami; 2 = adriani; 3 = alatus; 4 = amphius; 5 = armstrongi; 6 = babanango; 7 = beddardi; 8 = bergvillensis; 9 = bourquini; 10 = bulwerensis; 11 = colletti; 12 = crookesi; 13 = entumeni; 14 = gracilis; 15 = hedothecus; 16 = hlatikulu; 17 = injasuti; 18 = ivari; 19 = jasoni; 20 = lovuus; 21 = marleyi; 22 = martensi; 23 = michelleae; 24 = modestus; 25 = oresbiosus; 26 = ortyi; 27 = pajori; 28 = richerti; 29 = setosus; 30 = thornvillensis.