Tritogeniidae, Plisko, 2013

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 : 79-80

Family Tritogeniidae fam. n.

Type genus: Tritogenia Kinberg, 1867 .

Diagnosis: Body compact, shorter than 160 mm. Number of segments around 80, rarely over 100. Holandric (male funnels in segments 10 and 11), enclosed or free, posterior pair usually smaller than anterior. Two seminal vesicles attributed to segments 10 and 11, the posterior vesicle often smaller than the anterior vesicle. Excretory system meroic; two or more small nephridia per segment (except in some anterior segments, sometimes also absent from a few posterior segments). Oesophageal gizzards: one in 6–7 ( Tritogenia ), or two in 6–7 and 9 ( Michalakus ), the second much smaller and soft. Dorsal blood vessel double in segments 4–10, 11, 12, including when crossing septa; simple posteriad of segment 12. Four or five septa: 4/5–8/9 variably thickened, with septa 6/7 always attached to gizzard at various parts along its length. Setae difficult to see, being minute; on preclitellar segments noticeable only as a few pairs of cd, sometimes ab on various segments; on 9 and a few following, ab setae usually associated with papillae, occasionally extending on a few segments beyond clitellum; on post-clitellar segments eight per segment in four rows located ventrolaterally, although sometimes only ab may be noticeable, with cd difficult to trace; convergence of ab may occur on a few preclitellar segments, divergence postclitellarly.

Description: Unpigmented; live specimens ( Fig. 3 ) whitish or pinkish grey, body plump and compact; when preserved slightly extended, usually 25–100 mm, rarely reaching 150 mm; 3–15 mm wide at segment 10, much wider at tubercula pubertatis. Average number of segments 60–100, seldom exceeding 120. 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 characteristic for species. Female pores in 14. Male pores occur variably in clitellar area, although difficult to detect externally.

Clitellum is saddle-shaped.Tubercula pubertatis variable in shape. Spermathecae small, variably shaped, ampullae elongated, paired or multiple, with pores pretestical, testical, or post-testical; in one to six intersegmental furrows: 9/10–15/16, 16/17. Calciferous glands stalked or not, in segments 9, 10, 9–10. Genital glands variably shaped, either present or not.

Notes:Although no specific histological study on the musculature of Tritogeniidae species was conducted, it was noted that the external muscle bundles observed under microscopic magnification (usually 150–250×) differ in structure from those in Microchaetidae (s.str.). Future histological examination may shed more light on muscle differences, perhaps also providing an indication of evolutionary lineages for these two families.

Composition: There are two genera in this new family. The genus Tritogenia Kinberg, 1867 comprises the following 35 species: T. alveata Plisko, 1997 ; T. annetteae Plisko, 1997 ; T. ataxia Plisko, 1997 ; T. curiosa Plisko, 1997 ; T. curta Plisko & Zicsi, 1991 ( Fig. 4 ); T. debbieae Plisko, 2003 ; T. diversa Plisko, 1997 ; T. douglasi Plisko, 1997 ; T. grisea (Michaelsen, 1902) ; T. herbana Plisko, 1997 ; T. hiltonia Plisko, 2003 ( Fig. 5 ); T. howickiana (Michaelsen, 1913) ; T. insolita Plisko, 1997 ( Fig. 6 ); T. karkloofia Plisko & Zicsi, 1991 ; T. koilia Plisko, 1997 ( Fig. 7 ); T. kruegeri Plisko & Zicsi, 1991 ; T. liversagei Plisko, 1997 ; T. lunata Plisko, 1997 ; T. melmothana (Michaelsen, 1928) ; T. miniseta Plisko, 1997 ; T. monosticha Plisko, 1997 ; T. morosa Cognetti de Martiis, 1906 ; T. mucosa Plisko, 1997 ; T. ngelensis Plisko, 1997 ; T. ngomensis Plisko, 1992 ; T. palusicola Plisko, 1997 ; T. phinda Plisko, 2005 ; T. qudeni Plisko, 2003 ; T. shawi Plisko & Zicsi, 1991 ( Fig. 8 ); T. silvicola Plisko, 1997 ; T. soleata Plisko, 1997 ; T. sulcata Kinberg, 1867 ( Fig. 1 ); T. tetrata Plisko, 2003 ( Fig. 9 ); T. turneri Plisko, 1997 ; T. zuluensis (Beddard, 1907) ( Fig. 10 ).

Figures

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.

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