Bhawania Schmarda, 1861

Watson, Charlotte & Faulwetter, Sarah, 2017, Stylet jaws of Chrysopetalidae (Annelida), Journal of Natural History 51 (47 - 48), pp. 2863-2924 : 2876-2877

Genus Bhawania Schmarda, 1861

( Figures 6a–d , 7a–c ; Tables 1, 2)

Type species: Bhawania myrialepis Schmarda, 1861 . Material examined

Three specimens Bhawania amboinensis Horst, 1917 : NTM W . 23715, Darwin , Northern Territory, Arafura Sea (mCT-00002, mCT-00087); NTM W . 2311, Broome , Western Australia, Eastern Indian Ocean (mCT-00100); 1 specimen Bhawania cf . cryptocephala Gravier, 1901: NTM W. 25610, Spain, Mediterranean Sea (mCT-00003); 2 specimens Bhawania pottsiana Horst, 1917 : AM W . 36159, Dampier , Western Australia, Eastern Indian Ocean (mCT-00083, mCT-00084); 1 specimen, Bhawania cf . riveti ( Gravier, 1908) NTM W.26199, Thailand, Andaman Sea (mCT-00037).

Distribution

Bhawania species are found in tropical to sub-tropical waters in world oceans between 30°N and 30°S.

Habitat

Bhawania goodei Webster, 1884 (re-identified as Bhawania amboinensis, CW ) was reported co-habiting inside the burrows of three coral-boring sipunculan taxa, while Bhawania pottsiana was observed ‘lying along the length of the dorsal surface of its host’, namely the amphinomid polychaete Eurythoe complanata Pallas, 1766 ( Gibbs 1969) . Bhawania species have been found inside the canals of sponges, e.g. Bhawania amboinensis , collected live with brilliant yellow material in the gut, indicating possible ingestion of invertebrate material associated with the sponge host (CW pers. obs.) and Bhawania species associated with coral hosts, e.g. Bhawania riveti were found inside living Cyphastrea microphthalma ( De Lamarck, 1816) and Montipora De Blainville, 1830 (collection data, PMBC). Bhawania goodei has also been found among chaetopterid tubes attached to undersides of rocks, from sabellariid Phragmatopoma Mörch, 1863 reefs and amongst Dendropoma Mörch, 1861 infauna (CW pers. obs.). Bhawania species have been observed to be particularly slow moving and able to flatten their body against any hard surface (CW pers. obs.) among the deep crevicular habitats they inhabit in shallower waters of 0– 30 m.

General morphology

Mature specimens of Bhawania pottsiana measure ~ 50 mm for 300 segments and Bhawania amboinensis 25 mm length for 155 segments (CW pers. obs.). Bhawania species comprise large, broad chrysopetalids with a dorsum completely covered by flattened, golden brown to deep copper coloured, paleael notochaetal fans; main paleae possess raised ribs and tubercules ( Figure 6a ). Sensory structures include a small prostomium (fused with anterior segments) which is retractile in association with a large nuchal ridge, two pairs of complex eyes, large cylindrical palps, lateral organs and retractile styles of dorsal cirri. Ventral pads are present (CW pers. obs.).

Pharynx and jaws

Bhawania possesses a long slender proboscis, a long slender, partly differentiated pharynx extending to ca. segment 25, and posterior caecae ( Figure 6b, d ). The paired elongate jaws are triangular, robustly calcified and extend along the length of the proboscis. Jaws are situated very close to each other and overlap along approximately 3/4 of their margin. The degree of interlinking is seen clearly in posterior end view and cross sections ( Figures 6b–d , 7a–c ). The jaw margins appear straight with no obvious mid-way projections although a very small ridge is visible on the inner stylet margin, right at the point that the jaws diverge and flare out a little in the posterior quarter ( Figure 7a–c ). An outer, longitudinal, shallow dorsal ridge is observed in two species and evident only on the anterior half of the stylet jaw ( Figure 7c , anterior cross sections). The interior longitudinal groove is wide and shallow with the basal ends slightly flaring ( Figure 7a–c ).

Figures

Figure 6. Anterior end of Bhawania pottsiana (mCT-00084), imaged through micro-CT and rendered in 3D. (a) dorsal view; (b) dorsal view, virtually dissected to expose pharyngeal structures; (c) lateral view, semi-transparent rendering to show position of jaws; (d) lateral view, virtually dissected to expose pharyngeal structures.

Figure 7. Jaws of Bhawania spp., imaged through micro-CT. (a) B. amboinensis (mCT-00100), lateral view; (b) B. cf riveti (mCT-00037), posterior view; (c) B. amboinensis (mCT-00100), dorsal view and cross sections through the jaw along its length.