Bennelongia pinpi De Deckker, 1981

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 : 20-24

Bennelongia pinpi De Deckker, 1981

Figs 9-10

Remarks

Bennelongia pinpi De Deckker, 1981 was described from Pine Tree Creek Lagoon, north of Hughenden in Queensland, Australia. The species was characterized by its strongly pronounced beak-like expansion of the LV and the outline of the hemipenes (De Deckker 1981). At the time of the description these characters were unique and enabled a simple diagnosis of the species. Since then, two more species from within the same lineage have been described ( Martens et al. 2012) that are closely related to B. pinpi with respect to the absence of anteroventral lapel on the RV, the formation of a bulbous expansion in that place, and the hemipenis outline. Furthermore, some characters were found to be variable within B. pinpi upon examination of non-type populations, making the diagnosis of B. pinpi from its lineage sister taxa less obvious than is indicated in its description. Illustrations showing the variability within this species were needed to help elucidate the diagnostic characters that can be used for their identification. Thus, detailed drawings of the hemipenes and prehensile palps from non-type localities are provided, which alongside the B. pinpi description (De Deckker 1981) show the expected variability within the species and the characters that allow their diagnosis from the more recently described B. strellyensis Martens et al., 2012 and B. kimberleyensis Martens et al., 2012 .

Diagnosis (modified after De Deckker 1981)

Cp with pronounced anterior rostrum but bluntly pointed posterior; sub-triangular in right lateral view, circular in dorsal/ventral view (more so in females), LV overlapping RV on all sides, external valve surface smooth to pseudopunctate with sparsely distributed setae restricted to ventral and anteroventral region. LV with pronounced anteroventral beak-like expansion often extending below plane of horizontal ventral margin. RV with anteroventral flange or lapel absent, but with bulbous expansion of outer list in its place; anterior selvage with flange-like expansion and additional inner submarginal list. Rpp with proximal segment approximately two times as long as central width, distal palp segment short and triangular with rounded distal margin and apical sensory organ. Lpp with first segment over three times as long as central width; second palp segment sickle-shaped, short, and variably rounded, sometimes by over 180 degrees. Hemipenis with ls protruding well beyond ms, more so than any other described species in this lineage; ms forming a three dimensional structure, embracing ls on three sides, dorsal lobe with rounded distal margin.

Measurements (in µm)

Ƌ: RV: L = 1998-2095 (n =3), H = 1175-1218 (n =3). LV: L = 2208-2223 (n =3), H = 1293-1320 (n =3). Cp: L = 2063-2232 (n =9), W = 1285-1523 (n =3), H = 1258-1368 (n =3).

♀: RV: L = 2080-2103 (n =3), H = 1233-1273 (n =2). LV: L = 2200-2280 (n =2), H = 1288-1335 (n =2). Cp: L = 2055-2300 (n =7), W = 1195-1265 (n =5), H = 1218-1300 (n =2).

Localities investigated

Salt Lake, freshwater lake north of Hughenden on Kennedy Developmental Highway QLD, collected on 9 Jun. 2011 by RS and AK, coordinates: 19º51’19.9” S - 144º16’11.3” E (Sample QLDP11A).

Pelican Lake, north of Hughenden on Kennedy Developmental Highway QLD, collected on 9 Jun. 2011 by RS and AK, coordinates: 19º51’53.1” S - 144º15’20” E (Sample QLDP13A).

Lake Louisa, north of Hughenden on Kennedy Developmental Highway QLD, collected on 9 Jun. 2011 by RS and AK, coordinates: 19º53’45.6” S - 144º15’55.5” E (Sample QLDP12A).

Material investigated or illustrated

ƋƋ from Pelican Lake (W40043), Salt Lake (W40027) and Lake Louisa (W40035), with soft parts dissected in sealed slide, valves stored dry in a micropalaeontological slide. Three Ƌ carapaces from Pelican Lake (W40045-W40047), Salt Lake (W40029-W40031) and Lake Louisa (W40037-W40039) stored in a micropalaeontological slide.

♀♀ from Pelican Lake (W40044), Salt Lake (W40028) and Lake Louisa (W40036) with soft parts dissected in sealed slide, valves stored dry in a micropalaeontological slide. Three ♀ carapaces from Pelican Lake (W40048-W40050), Salt Lake (W40032-W40034) and Lake Louisa (W40040-W40042) stored in a micropalaeontological slide.

Several in toto specimens in EtOH from Pelican Lake (W40080).

Differential diagnosis

Bennelongia pinpi can be diagnosed as within the B. pinpi lineage due to its large carapace, well developed anterior rostrum, blunt posterior, the bulbous expansion of the valve in place of the absent anteroventral lapel of the RV, the well-developed anteroventral beak-like expansion of the LV and the well sclerotized hemipenes with a three dimensional ms enveloping the ls.

It can be distinguished from the other species in this lineage by the elongated first Lpp segment (shorter in B. strellyensis Martens et al., 2012 and B. kimberleyensis Martens et al., 2012 ), the rounded dorsal margin of the Rpp second segment (triangular-pointed in B. kimberleyensis Martens et al., 2012 ), the narrow ls of the hemipenis (broader in B. strellyensis Martens et al., 2012 and B. kimberleyensis Martens et al., 2012 ) and the extension of the ls far beyond the ms (much less extended in B. strellyensis Martens et al., 2012 and B. kimberleyensis Martens et al., 2012 ).

Additional description (modified after De Deckker 1981)

Cp ( Fig. 9 E-H) with pronounced anterior rostrum but bluntly pointed posterior; sub-triangular in right lateral view ( Fig. 9 K-L), circular in dorsal/ventral view (more so in females), LV overlapping RV on all sides, external valve surface smooth to pseudopunctate with sparsely distributed setae restricted to ventral and anteroventral region.

LV ( Fig. 9A, C ) with pronounced anteroventral beak-like expansion, often extending below plane of horizontal ventral margin, dorsal margin highest at valve mid-point.

RV ( Fig. 9B, D ) in lateral view with dorsal margin highest at valve mid-point; anteroventral flange or lapel absent, but with bulbous expansion of outer list in its place ( Fig. 9 I-J); anterior selvage with flangelike expansion, and additional inner submarginal list.

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

Rpp ( Fig. 10D ) with first segment approximately two times as long as central width, subapically with two slender sensory organs, one long and one short often overlapping; second palp segment short and triangular with rounded distal margin and apical sensory organ.

Lpp ( Fig. 10C, D ) with first segment over three times as long as central width, subapically with one sensory organ; apically with rounded outgrowth; second palp segment sickle-shaped, short, and variably rounded ( Fig. 10C versus Fig. 10E ), sometimes by over 180 degrees with distal sensory organ.

Hemipenes ( Fig. 10 A-B) with width of ls variable depending on slide preparation ( Fig. 10a vs Fig. 10B ), ls protruding well beyond ms, more so than any other described species in this lineage; ms consisting of three lobes, distal part of ms produced into a three-dimensional lobe embracing the ls on proximal and distal sides, a small additional dorsal lobe with rounded distal margin, and a proximal lobe nearly straight and incomplete.

Ecology and distribution

The distribution of B. pinpi appears to be isolated to an area north of Hughenden. At the time of its description, the species had been found in Pine Tree Creek Lagoon, Agnes Lake, Salt Lake and Louisa Lake (De Deckker 1981). It appears that most of these populations still exist. Here, an additional locality (Pelican Lake) is recorded.

Figures

Fig. 9. Bennelongia pinpi De Deckker, 1981, all from Salt Lake, north of Hughenden, QLD. A. ♀, LVi (W40028). B. ♀, RVi (W40028). C. Ƌ, LVi (W40027). D. Ƌ, RVi (W40027). E. ♀, Cp dorsal (W40030). F. ♀, Cp ventral (W40031). G. Ƌ, Cp ventral (W40032). H. Ƌ, Cp dorsal (W40034). I. Ƌ, RVi detail anteriorly (W40027). J. Ƌ, RVi detail anteriorly (W40027). K. Ƌ, CpRl (W40033). L. ♀, CpRl (W40029). Scales: A-H, K-L = 1000 μm, J-I = 100 μm.

Fig. 10. Bennelongia pinpi De Deckker, 1981. (A-D = W40043 from Pelican Lake QLD, E = W40035 from Lake Louisa QLD). A-B. Outlines of hemipenes. C. Left prehensile palp. D. Right prehensile palp. E. Left prehensile palp. Scales: A-B = 156.3 μm, C-D = 89.3 μm, E = 42.6 μm.