Bennelongia gwelupensis Martens, Halse & Schön, 2012

Deckker, Patrick De & Martens, Koen, 2013, Extraordinary morphological changes in valve morphology during the ontogeny of several species of the Australian ostracod genus Bennelongia (Crustacea, Ostracoda), European Journal of Taxonomy 36, pp. 1-37 : 9

Bennelongia gwelupensis Martens, Halse & Schön, 2012

Figs 22-24

Specimens of B. gwelupensis were chosen from 2 different localities (DJC13, Arro Swamp: Fig. 22 , and DJC 29, Katanning Rd pool: Fig. 23 ) so as to determine whether there may be some morphological differences in valve ornamentation between sites. This species belongs to the Bennelongia australis – lineage (see discussion in Martens et al. 2012).

Unfortunately, we were unable to get A-3 and A-4 instars of this species from either locality, but it is evident that the 2 domes are present at least in the A- 2 specimens, while only the posterior one is visible in A- 1 specimens ( Figs 22 , 23 ). What is striking, nevertheless, is the pseudo-punctation in juvenile stages, and the presence of a large number of cones with outer lips and setae. Well over 30 of these are seen in both valves, and they are more prominent at the A-2 stage ( Fig. 22 ). Comparison between A- 1 specimens from the 2 localities ( Figs 22-23 ) shows that the location of the cones on the valves are very similar, and this again points to a genetic determination of their placement; they are not controlled by water chemistry.

Finally, the broad and calcified inner lamella with the inner list is present in A- 1 juveniles ( Fig. 23 bottom right). We dissected some further A- 1 specimens of this species, and could confirm that the soft parts are typical of an A- 1 juvenile, i.e., undeveloped reproductive organs and A2 with 4+1 natatory setae (5+1 setae occur in adult Cyprididae ).

Figures

Fig. 22. External views of carapaces of Bennelongia gwelupensis Martens et al., 2012 from Arro Swamp. Right lateral views in left column for adult, A-1 and A-2 specimens, and dorsal views on the right of A-1 and A-2 specimens. Note that the ornamentation becomes progressively more intricate at younger stages.

Fig. 23. External views of Bennelongia gwelupensis Martens et al., 2012 from Katanning Road pool, except for the middle image on the right which shows an internal view of a LV. Top left image represents the right lateral view of an adult carapace, with the antero-ventral beak-like expansion of the LV. In the internal view of the A-1 LV, note the depressions seen internally that mirror the cones that occur externally. A prominent inner list is visible all along the periphery of the valve, except in the dorsal region. This latter feature is usually not seen in juveniles ostracods.

Fig. 24. Internal views of juvenile specimens of Bennelongia gwelupensis. Top row. internal views of A-2 juveniles from Arro Swamp (LV on left and RV on right with appendages). Second row. details of internal views of anterior RV (tilted) of A-1 specimen from Katanning Road pool on left, and A-2 on right which is the same specimen as the image above, but tilted. Third row. internal views of A-1 juveniles from Katanning Road pool (LV on left and RV on right); same specimen as detail left above. Bottom row.detail of internal views of RV on left and of LV on right; both are the same A-1 specimens as the images above, to show that the pores on the cones connect with the inside of the valve.