Bennelongia cuensis

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 : 27-30

Bennelongia cuensis sensu lato

Figs 12-13

Diagnosis

Cp large (L = 1800 µm) with strong anterior rostrum and bluntly pointed posterior in dorsal view. LV strongly overlapping RV on all sides, LV with straight dorsal margin and bluntly pointed anteroventral beak. RV with broad and elongated anteroventral lapel running parallel to the selvage. Hemipenis with distal margin of ms straight and broad, producing a pointed ventral and a rounded dorsal lobe; ls asymmetrical in the two hemipenes: one with distal thumb-like expansion, the other without; tips of ls and ms in both hemipenes well separated; ls extending well beyond ms. Rpp with distal segment sub-triangular, rounded on dorsal margin, elongated and with narrow base. Lpp with proximal segment apically with small triangular outgrowth; distal segment sickle shaped, of equal length to proximal segment, distal half with parallel margins. Ratio for maximum length of Lpp distal segment to length of hemipenis ms distal margin 1:1.7. Ratio for maximum length Rpp distal segment to length of hemipenis ms distal margin approximately 1:1.3.

Remarks and Etymology

Two populations from the Paroo region of eastern Australia constitute a molecular lineage that is morphologically similar, but genetically distinct from B. cuensis Martens et al., 2012 . Although some minor morphological differences have been found for Western Australian animals (provided in the description below), these do not appear to constitute reliable differences. Analysis of additional populations may enable the identification of more reliable diagnostic characters in the future. Therefore, this lineage is here not formally described as a different species from B. cuensis Martens et al., 2012 .

Measurements (in µm)

Ƌ: RV: L = 1815-1863 (n =2), H = 1043-1090 (n =2). LV: L = 1955-1978 (n =2), H = 1155-1165 (n =2). Cp: L = 1865-1892 (n =5), W = 1000-1027 (n =3), H = 1113-1123 (n =2).

♀: RV: L = 2053-2113 (n =2), H = 1198-1270 (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

Unnamed pool, Kilcowera Station, south of Thargomindah QLD, coordinates: 28°40’13.2” S - 143°54’10.4” E. Material used for the present illustration was collected on 14 Jun. 2011 by AK (Sample QLDP19A).

Island claypan, on Bloodwood Station, north west of Bourke NSW, collected 28 Sep. 2010 by Brian Timms, coordinates: 29°29’ S - 144°49’ E (Sample NSWB1).

Material investigated

Ƌ from unnamed pool, Kilcowera Station QLD (W40052) and four ƋƋ from island claypan, Bloodwood Station NSW (W40001-W40004), with soft parts dissected in a sealed slide and valves stored dry in a micropalaeontological slide.

Two ♀♀ from island claypan, Bloodwood Station NSW (W40011-W40012), with soft parts dissected in a sealed slide and valves stored dry in a micropalaeontological slide.

♀ from unnamed pool, Kilcowera Station QLD (W40051), with soft parts dissected in a sealed slide and valves stored dry in a micropalaeontological slide.

Three Ƌ carapaces stored in a micropalaeontological slide (W40054-W40056), three ♀ carapaces stored in a micropalaeontological slide (W40057-W40059). ♀ (W40053) with valves stored dry in a micropalaeontological slide, all from unnamed pool, Kilcowera Station QLD.

Three Ƌ carapaces from island claypan, Bloodwood Station NSW (W40005-W40007), three ♀ carapaces stored in a micropalaeontological slide (W40008-W40011).

Several in toto specimens in EtOH, from unnamed pool, Kilcowera Station QLD (W40078).

Several in toto ♀ specimens in EtOH, from island claypan, Bloodwood Station NSW (W40079).

Differential diagnosis

The species belongs to the B. australis lineage due to its large size (L = 1800 µm), the strong anterior rostrum in dorsal view and the presence of an anteroventral lapel on the RV. It can be distinguished from the other species in this lineage by the straight dorsal margin of the LV (less so in B. gwelupensis Martens et al., 2012 and B. coondinerensis Martens et al., 2012 , the well separated tips of the ls and the ms of both hemipenes (close in B. bidgelangensis Martens et al., 2012 ), the considerable overlap of the RV by the LV, sub-quadrate outline of the Cp in lateral view, the narrow lobes of the ms (limited overlap of RV by LV, rounded Cp outline and blunt ms lobes in B. lata Martens et al., 2012 and by the smaller Rpp to hemipenis ratio (maximum length of Rpp second segment to distal margin of Hp ms approximately 1: 1.3 in B. cuensis sensu lato, 1: 2.2 in B. cuensis Martens et al., 2012 ).

Additional description

Male and female carapaces ( Fig. 12 E-H, K-L) in right lateral view with straight dorsal margin, LV overlapping RV on all sides, particularly dorsally, greatest height situated throughout the middle third of the Cp length; greatest Cp width situated near the middle in dorsal and ventral view, anterior side with a rostrum and posterior side pointed; Cp surface set with short setae and weakly pitted. Male carapaces and valves slightly smaller than in the female, but with very similar shape.

Male and female LV ( Fig. 12A, C ) with straight dorsal margin, greatest height situated throughout the middle third of the valve length, anteroventral beak bluntly pointed.

Male and female RV ( Fig. 12B, D ) with greatest height situated slightly anterior of middle in lateral view, dorsal margin rounded; posterior selvage sub-marginal, inner list merging with selvage posteriorly; selvage expanded and striate at vicinity of anteroventral lapel ( Fig. 12 I-J); lapel mildly striate, broad and running parallel to selvage ( Fig. 12 I-J).

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

Rpp ( Fig. 13A ) with first segment length approximately 1.5 times its central width; subapically with two sensory organs, the proximal one long and slender, the distal one short; second palp segment nearly as long as the first one, with a narrow base and bluntly rounded dorsal margin, ratio for maximum length of second segment to length of hemipenis ms distal margin approximately 1:1.3, distally with small sensory organ.

Lpp ( Fig. 13B ) with first segment approximately two times its central width, subapically with one long proximally based and one short distally based sensory organ, apically with rounded outgrowth; second segment sickle shaped, equal in length to first segment, ratio for maximum length of second segment to length of hemipenis ms distal margin approximately 1:1.7, distal half straight with almost parallel margins, distally with small sensory organ.

Hemipenes ( Fig. 13 C-D) asymmetrical, one hemipenis with ls distally bluntly pointed ( Fig. 13C ), the other with ls more sharply pointed with thumb-like expansion ( Fig. 13D ); bluntly pointed ls of one hemipenis often folding at rounded dorsal margin suggesting the presence of a three dimensional structure; both hemipenes with ls and ms tips well separated, ls extending beyond ms, ms ventrally pointed and dorsally with rounded lobe.

Ecology and distribution

This cryptic lineage appears to have only a limited distribution near the Paroo region of south western Queensland and north western New South Wales. The species was found in high abundance in a turbid pool with grass and small aquatic weeds on Kilcowera Station.

Figures

Fig. 12. Bennelongia cuensis sensu lato A-B, D-L from unnamed pool near Kilcowera Station, QLD; C from island claypan on Bloodwood Station NSW. A. ♀, LVi (W40053). B. ♀, RVi (W40053). C. Ƌ, LVi (W40002). D. Ƌ, RVi (W40052). E. ♀, Cp dorsal (W40059). F. ♀, Cp ventral (W40058). G. Ƌ, Cp ventral (W40056). H. Ƌ, Cp dorsal (W40055). I. Ƌ, RVi detail anteriorly (W40052). J. Ƌ, RVi detail anteriorly (W40052). K. Ƌ, CpRl (W40054). L. ♀, CpRl (W40057). Scales: A-H, K-L = 1000 μm, J = 200 μm, I = 100 μm.

Fig. 13. Bennelongia cuensis sensu lato, all from unnamed pool near Kilcowera Station, QLD, Ƌ (W40052). A. Right prehensile palp. B. Left prehensile palp. C. Hemipenis. D. Outline of other hemipenis. Scales: A-B = 89.3 μm, C-D = 104.2 μm.