Bennelongia mckenziei, Shearn, Rylan, Koenders, Annette, Halse, Stuart & Martens, Isa Schön and Koen, 2012

Shearn, Rylan, Koenders, Annette, Halse, Stuart & Martens, Isa Schön and Koen, 2012, A review of Bennelongia De Deckker & McKenzie, 1981 (Crustacea, Ostracoda) species from eastern Australia with the description of three new species, European Journal of Taxonomy 25, pp. 1-35 : 14-16

Bennelongia mckenziei sp. nov.

urn:lsid:zoobank.org:act:321592CE-0627-4962-96CB-F1C7D26F6D8A

Fig. 6

Diagnosis

Cp small (L = 1000 µm), in dorsal view with reduced anterior rostrum, blunt posterior and reduced anteroventral overlap of LV over RV; in lateral view with rounded dorsal margin, no visible anteroventral lapel and greatest height at the middle; LV with greatest height at the middle, anteroventral beak-like expansion not pointed, instead expressed as a linear horizontal extension of the LV ventral margin; RV with rounded margin near posterodorsal hinge, greatest height slightly anterior to the middle, anteroventral area without lapel, but with an expansion of the selvage.

Males unknown.

Etymology

This species is named after Dr K. McKenzie, who described the Bennelongia genus together with Dr P. De Deckker in 1981.

Type material

Holotype

♀ (W40071), with soft parts dissected in a sealed slide, RV and LV stored dry in a micropalaeontological slide.

Paratypes

♀ (W40068) with soft parts dissected in a sealed slide, two ♀ carapaces stored in separate micropalaeontological slides (W40072-W40073), ♀ LV (W40069) and ♀ RV (W40070) stored dry in a micropalaeontological slide.

Type locality

Horseshoe Lagoon, Kilcowera Station, south of Thargomindah QLD, coordinates: 22º25’55.4” S - 145º42’27.2” E. Material used for the present description was collected on 16 Jun. 2011 by AK (Sample QLDP 21C).

Measurements (in µm)

♀: RV: L = 1082, H = 660. LV: L = 1078, H = 626. Cp: L = 1008-1060 (n =2), W = 618-647 (n =2), H = 622.

Other material investigated

Cardenyabba Lagoon, Kilcowera Station, south of Thargomindah QLD, collected by AK on 14 Jun. 2011, coordinates: 28º41’23.2” S - 143º56’35” E. This population was the same Evolutionary Genetic species ( Birky & Barraclough 2009) as the type population, which confirmed morphological evidence that they belong to the same species as the type population.

Differential diagnosis

Bennelongia mckenziei sp.nov. belongs to the B. barangaroo lineage, because of its relatively small carapace size (L = 1000 µm), rounded dorsal margin, less pronounced anterior rostrum in dorsal view, less pronounced beak structure of the LV and reduced anteroventral overlapping of LV over RV. It can be distinguished from the other species in this lineage ( B. dedeckkeri sp. nov. and B. barangaroo De Deckker, 1981 ) by the fact that the greatest height of the Cp is at the middle (slightly anterior in B. dedeckkeri sp. nov.), the rounded posterodorsal margin of the RV hinge (straight in B. dedeckkeri sp. nov.), the absent anteroventral lapel of the RV (present in B. barangaroo and B. dedeckkeri sp. nov.), the rounded anteroventral margin of the LV (pointed in B. dedeckkeri sp. nov. and B. barangaroo ), and the straight ventral margin of the LV extending to the distal point of the beak (sinuous ventral margin and more pronounced anteroventral beak structure in B. dedeckkeri sp. nov. and B. barangaroo ). As no males are known for this species, we cannot compare shapes of prehensile palps and of hemipenes.

Additional description of female

Cp in dorsal and ventral view egg shaped ( Fig. 6C, E ), with blunt anterior and posterior ends; in lateral view ( Fig. 6D ) with rounded dorsal margin, greatest height in the middle, LV overlapping RV on all sides, overlap narrow at middle of dorsal margin; external valve surface hirsute with setae approximately 50 µm in length.

LV ( Fig. 6A ) with rounded dorsal margin, greatest height at the middle, anteroventral beak-like expansion not pointed, instead expressed as a linear horizontal extension of the LV ventral margin; ventral margin straight over c. two thirds of its length.

RV ( Fig. 6B , F-G) with rounded dorsal margin, rounded margin near posterodorsal hinge, greatest height situated slightly anterior of the middle; outer list with ventral row of tubercles; posterior inner list submarginal, but merging with selvage at beginning of dorsal hinge; anteroventral area without lapel or bulbous expansion of the valve margin, instead only an expansion of the selvage in this area visible.

Female appendages as typical of the genus and without special features.

Male unknown.

Ecology and distribution

The species has been recorded in a limited distribution, namely two localities on Kilcowera Station, south of Thargomindah QLD. No males were found in either of the two recorded localities, which suggested the populations were parthenogenetic, particularly in Cardenyabba Lagoon where it was recorded sympatrically with B. dedeckkeri sp. nov.

Figures

Fig. 6. Bennelongia mckenziei sp. nov., all from Horseshoe Lagoon, QLD (Type locality). A. Holotype ♀, LVi (W40071). B. Holotype ♀, RVi (W40071). C. ♀, Cp dorsal (W40072). D. ♀, CpRl (W40073). E. Holotype ♀, Cp ventral (W40071). F. Holotype ♀, RVi detail anteriorly (W40071). G. Holotype ♀, RVi detail anteriorly (W40071). Scales: A-E = 500 μm, F-G = 100 μm.