Tritogenia howickiana (Michaelsen, 1913)

Nxele, Thembeka C., 2012, The megadrile fauna (Annelida: Oligochaeta) of Queen Elizabeth Park, South Africa: species composition and distribution within different vegetation types, African Invertebrates 53 (2), pp. 543-543 : 546

Tritogenia howickiana (Michaelsen, 1913)

Figs 2–5

Microchaetus sulcatus var. howickianus: Michaelsen 1913: 432 ; Reynolds & Cook 1976: 115.

Tritogenia howickiana: Michaelsen 1918: 333 ; Plisko & Zicsi 1991: 112; Plisko 1992: 368; 1997: 280; 2003: 317.

Type locality: South Africa, KwaZulu-Natal, Howick .

Description:

External: Body length 57–80 mm, width 6–8 mm. Number of segments, 81–103. Prostomium prolobous, small. Segmentation, preclitellar segments with secondary annulations: segments 1–3 simple with horizontal grooves, segments 4–8 with two ringlets of equal size, 9 with second ringlet smaller, from 10 and postclitellar simple and randomly annulated. Setae ab only visible from 7, 9 or 10, other setae may be seen from 10. Male pores not observed. Female pores minute, on anterior part of segment 14 near ab setae. Spermathecal pores minute, in 11/12 and 12/13 intersegmental furrows. Clitellum saddle-shaped, on 13–21; segmented, dorsal borders well marked. Tubercula pubertatis on 18, 19–21, nearly square glandular swellings ( Fig. 3 ). Genital papillae on 11–18, 22, 23, paired or single, variable in size, round swellings on ab setae.

Internal: Septa 4/5, 5/6, 6/7 strongly thickened; 7/8, 8/9 are also thickened but less so than the anterior ones ( Fig. 4 ); other septa thin. Gizzard well developed in 6–7, globular, muscular. Calciferous glands in 9–10, stalked. Intestinal origin in 12. Dorsal blood vessel double in the anterior segments, double even when crossing septa; simple in the posterior segments. Nephridia, in posterior segments two pairs per segment, coiled; the dorsal pair larger and the ventral smaller, this varying between segments, in some the dorsal smaller and the ventral larger. Holandric. Testes funnels are closely paired with the second pair somewhat differently shaped and smaller, both pairs iridescent. Seminal vesicles small in 10 and 11; one pair per segment. Spermathecae variable in shape in 12 and 13, more than one pair per segment ( Fig. 5 ).

Material examined: 7 cl. and 37 juv. specimens: Woodland, on the side of the road near fence (29°34.810'S 30°19.217'E), 23.ii.2012, 2 cl., NMSA /Olig.06106; Woodland, small grass with bush near road (29°34.345'S 30°19.377'E), 7.i.2012, 1 cl., NMSA /Olig.06094; Mixed Scrub, between plantation and grassland (29°33.683'S 30°18.992'E), 3149 ft, 24.ii.2012, 4 juv., NMSA /Olig.06130; 7 juv., NMSA /Olig.06132; 5 juv., NMSA /Olig.06194; 4 cl., NMSA /Olig.06131; Grassland, medium grass with a few trees (29°34.252'S 30°19.174'E), 7.i.2012, 20 juv., NMSA /Olig.06134 & 06135; Grassland, open patch of grass (29°34.123'S 30°19.153'E), 7.i.2012, 1 juv., NMSA /Olig.06139 .

Remarks: The only indigenous species collected, with its type locality in Howick (ca 15 km north of QEP), and possibly endemic to narrow midlands area of KZN. Placed in the T. sulcata species-group, to which the following belong: T. sulcata Kinberg, 1867 , T. howickiana (Michaelsen, 1913) , T. debbieae Plisko, 2003 , and T. hiltonia Plisko, 2003 , all occurring in close proximity. The similar/distinguishing characters noted in these species are shown in Table 1. Because the type material of sulcata and howickiana ( Fig. 2 ) is in poor condition internally and comparative anatomical study may be not productive, the published data ( Michaelsen 1899, 1913; Plisko & Zicsi 1991) are considered. Material from QEP differs from type material of debbieae and hiltonia kept at the NMSA in thickness of the septa, shape and position of papillae, and number of spermathecae, indicating a close resemblance to the description of howickiana . Therefore, the specimens from QEP are assigned to this species. However, the known characters of the taxa in the sulcata -group are closely related (Table 1); a systematic revision based on molecular study is suggested.

Figures

Fig. 2. Tritogenia howickiana Kinberg, 1867, the whole body of the lectotype. Scale bar = 5 mm.

Figs 3, 4. Tritogenia howickiana: (3) anterior part of the body, showing papillae and tubercula pubertatis ventrally; (4) dorsal dissection showing thickened septa.Abbreviations:Cl – clitellum, DB – double blood vessel, P – papillae of 15–17, S – septa 4/5–6/7, Tp – tubercula pubertatis,.

Fig. 5. Tritogenia howickiana, position of the spermathecae (Sp) in segments 12 and 13.