Tritogenia Kinberg, 1867

Plisko, Jadwiga Danuta, 2013, A new family Tritogeniidae for the genera Tritogenia and Michalakus, earlier accredited to the composite Microchaetidae (Annelida: Oligochaeta), African Invertebrates 54 (1), pp. 69-69 : 83-84

Genus Tritogenia Kinberg, 1867

Figs 1–10

Brachydrilus: Benham 1888: 72 (sp.); Michaelsen 1900: 462 (for benhami , with type locality unknown); Michaelsen 1918: 332; Stephenson 1930: 900; Reynolds & Cook 1976: 77 (for benhami , with a note ‘ Typus amissus’).

Microchaetus: Michaelsen 1902: 33 (for griseus ); Michaelsen 1907: 6 (for zulu that later became a junior synonym of T. zuluensis Beddard, 1907 ); Michaelsen 1913:431 (for T.sulcata and T. howickiana ); Reynolds & Cook 1976: 77, 192 (with a note for griseus ‘ Typus amissus’, incorrect attribution of Michaelsen’s authorship to zuluensis .

Type species: Tritogenia sulcata Kinberg, 1867 . Type material NHRS 157 ( Fig. 1 ). Type locality: [ RSA, KZN] ‘ Port Natal’ [= Durban, RSA] (Kinberg 1867: 97) .

Diagnosis: Two or more small nephridia per segment (except for three anterior segments, sometimes also missing in a few posterior segments). One oesophageal gizzard in 6–7. Dorsal blood vessel double in segments 4–10, 11, 12; double when crossing septa; single after segment 10, 11 or 12. Four or five septa variably thickened, with septa 6/7 attached externally and anteriorly to various parts of the gizzard.

Description: Annulation of pre-clitellar segments present; 1–3 usually simple, 4–9, 10 ringleted, with 2–4 ringlets annulated or not, with an external segmental subdivision; first ringlet usually longer than second. Post-clitellar segments may or may not be externally subdivided. Setae: extremely small and irregularly placed; on preclitellar segments, may be recognizable under high magnification (120–250×) and only as a few pairs of ab or cd; sometimes ab seen only on a few segments. As from segment 9, ab may be associated with papillae, which occasionally extend on a few segments beyond clitellum. On post-clitellar segments, setae easier to notice, although variably placed; might be in four pairs located mostly ventrally, with ab and cd paired very closely, or distantly, with aa 2–3 times as bc; dd nearly 0.60–0.70 of U. In some species, ab on a few preclitellar segments may slightly converge, diverging postclitellarly. Occasionally cd not noticeable, when ab easily noted. Papillae and genital glands variably shaped, with segments on/in which they occur varying, occasionally associated with genital setae. Male pores occur variably in the area of tubercula pubertatis, although the pores are difficult to detect externally and are species-specific. Spermathecae small, often deeply embedded in body tissue; variably shaped, paired or multiple; in the majority of species they are close to septa 11/12 and 12/13, although in some species may be located in more segments, sometimes up to six.

Distribution: The genus is known only from a restricted area of the north-eastern part of the RSA, extending from the northern border of the Eastern Cape province through KZN and Mpumalanga and reaching Limpopo province. Occurrence in one or more of the neighbouring countries ( Lesotho, Botswana, Zimbabwe, and/or Swaziland) is possible or, in fact, likely.

Figures

Fig.1. Tritogenia sulcata Kinberg, 1867, type material fragments (NHRS 157; photo by E. Sigvaldadóttir).

Fig. 2. Tritogenia howickiana (Michaelsen, 1913), lectotype (ZMUH V-7658). Scale bar = 5 mm.

Fig. 3. Tritogenia sp., live specimens: (A) juvenile; (B) specimen developing tubercula pubertatis. (Photo by H. Grobler)

Figs 4–7. Paratypes of (4) Tritogenia curta Plisko & Zicsi, 1991; (5) T.hiltonia Plisko, 2003; (6) T.insolita Plisko, 1997; and (7) T. koilia Plisko, 1997. Scale bars = 1 cm.

Figs 8–10. Tritogenia species: (8) T. shawi Plisko & Zicsi, 1991, material from the area adjacent to the type locality; (9) T. tetrata Plisko, 2003, paratype; (10) T. zuluensis (Beddard, 1907), syntype. Scale bars = 1 cm.