Michalakus Plisko, 1996

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 : 84-85

Genus Michalakus Plisko, 1996

Fig. 11

Type species: Michalakus initus Plisko, 1996 . Holotype NMSA /Olig.00868 ( Fig. 11 ). Type locality: RSA, KZN, Albert Falls (29°28'S 30°27'E), near small stream, grassland, moderately wet soil.

Diagnosis: Two gizzards: one in segment 6–7, large, muscular, with septa attached at ⅓ of its length; second in 9, much smaller than the first, anteriorly muscular, soft posteriorly. Dorsal blood vessel double in 4–11, 12 and when crossing septa 4/5–11/12; single, although thick, in 13 and the following segments. Two pairs of nephridia per segment, noticeable in posterior segments; dorsal pairs with long thin tubes; ventral pairs close to median body line, with shorter tubes. Five variably thickened septa: 4/5–8/9.

Description: Secondary annulation exists in some anterior segments: 1–3 short, simple, with irregular longitudinal grooves; 4–6 with 2 simple ringlets similar in size and appearance; 7–9 with two ringlets, randomly annulated; 10–12 superficially divided into two annuli; clitellar segments dorsally simple, ventrally irregularly annulated; postclitellar segment simple, randomly annulated. Setae minute, closely paired; first pairs of ab visible only under 250× magnification on segment 7; post-clitellar setae larger, easier to observe. Nephridial pores not seen. Female pores in 14, minute openings in front of ab. Male pores not detected externally, possibly present in 16, where vasa deferentia abruptly insert into the body tissues. Clitellum saddle-shaped, segmented, whitish grey, extended dorsally between ab setal lines. Tubercula pubertatis below clitellar edges; in live specimen, manifest as glandular swellings; when preserved as three glandular swellings, clearly divided by intersegmental furrows, ventrally separated by distinct field. Papillae present, paired or single, small swellings in ab setal lines on some preclitellar and postclitellar segments. Septa: 4/5, 5/6 and 6/7 thickened most, 7/8 and 8/9 thickened less than anterior septa. Spermathecae minuscule with no diverticula, various shapes: ampullae are elongated tubes, bent or serpentine, close to septa 10/11, 11/12 and 12/13, spermathecae paired, or occasionally only two of them at one side.

Distribution: At present, the only known species occurs in the KZN Midlands, although more species may eventually be found in nearby areas.

Figures

Fig. 11. Michalakus initus Plisko, 1996, holotype.