Vigtorniella Kiseleva, 1996

Watson, Charlotte & Faulwetter, Sarah, 2017, Stylet jaws of Chrysopetalidae (Annelida), Journal of Natural History 51 (47 - 48), pp. 2863-2924 : 2901-2902

Genus Vigtorniella Kiseleva, 1996

( Figure 21a, b ; Tables 1, 2)

Type species: Vigtorniella zaikai ( Kiseleva, 1992)

Material examined

One specimen Vigtorniella zaikai: SIO-BIC A 5639, Black Sea

Distribution

Vigtorniella is a monotypic taxon represented by the species Vigtorniella zaikai which at present appears endemic to the Black Sea. Other species previously placed in Vigtorniella ( Vigtorniella flokati Dahlgren, Glover, Baco and Smith, 2004 and Vigtorniella ardabalia

Wiklund, Glover, Johannessen and Dahlgren, 2009) were recently moved to Boudemos ( Watson et al. 2016) .

Habitat

Vigtorniella zaikai larvae are found in plankton horizons at 250– 150 m with bottom depths to ~ 1300 m. Benthic adults are found at the narrow transition layer between upper oxygenated waters and lower anoxic waters at the boundary of the hydrogen sulphide zone in ~ 150 m in the Black Sea. Vigtorniella zaikai larvae were raised in the laboratory and the adults observed to feed in the flocculent layer of microbial mats that formed atop anoxic muds ( Zaikai et al. 1999). Adults are also reported from Black Sea methane seep areas (extended references in Watson et al. 2016).

General morphology

Vigtorniella zaikai possesses a very small body: planktonic larvae measure ~430 µm length ( Figure 21a ) with mature individuals <2 mm length and 14 segments. Sensory structures include very small, ovoid, partly fused palps; prostomial and body segment ciliation; eyes are absent ( Table 2). In common with other free-living calamyzins, Vigtorniella lacks a median antenna and possesses differentiated lateral antennae and palps, long spinous, slender notochaetae and slender compound falcigerous neurochaetae ( Aguado et al. 2013; Watson et al. 2016).

Pharynx and jaws

Vigtorniella zaikai has a short, muscular pharynx with broad internal septa, caeca, a very small proboscis with terminal papillae, and a pair of very small jaws ( Figure 21a, b ; Watson et al. 2016, figure 3d, e). Larval jaws are situated close together and each one is composed of a flat anterior part with a tanned brown, serrate tip, an asymmetrical flare mid-way, and a hollow groove visible in the curve at the point where the anterior platelet jaw connects with the posterior, elongated jaw ( Figure 21b ). In adults, only the anterior platelet jaw is visible ( Watson et al. 2016, figure 3E, 4B).

Figures

Figure 21. Vigtorniella zaikai, microphotographs, (a) planktonic nectochaete larva, dorsal view; (b) detail of stylet jaws in (a) (a, b from Watson et al. 2016).