Bennelongia triangulata, Martens, Halse & Schon, 2015

Martens, Koen, Halse, Stuart & Schön, Isa, 2015, On the Bennelongia nimala and B. triangulata lineages (Crustacea, Ostracoda) in Western Australia, with the description of six new species, European Journal of Taxonomy 111, pp. 1-36 : 26-31

Bennelongia triangulata sp. nov.

urn:lsid:zoobank.org:act:2EE84F9D-40BD-4866-9E42-5B6815D95E1A

Figs 11 A–M, 12A–M, 13A–G

Bennelongia sp. nov. 414 – Halse et al. 2000: table 4, appendix 4.

Bennelongia n. sp. 414 – Pinder et al. 2010: appendix 2.

Bennelongia sp. 414 nov. sp. – De Deckker & Martens 2013: 7–8 , figs 11–12.

Abbreviated description

Valves in inner view ( Figs 11A, C, H, J ; 12A, C, H, J ) subtriangular, with greatest height situated either in the middle or just before the middle; ventral margin almost straight, with weak mandibular curve. LV ( Figs 11A, H ; 12A, H ) with antero-distal il running only halfway along the anterior valve margin, antero-proximal il running slightly beyond halfway up along the valve margin, this list dorsally strongly S-shaped; posterior il smooth, not tuberculate, and running only along ventral margin. RV ( Figs 11C, J ; 12C, J ) with antero-ventral lapel a very narrow ridge, but valve margin protruding beyond selvage as in the Bennelongia pinpi lineage ( Figs 11C , I–M; 12C–D, G, I–J, L–M). Valves with delicate external ornamentation, consisting of small tubercles ( Figs 11D, G, L ; 12G, I, M ).

Cp ( Fig. 11B , D–G, L) with moderate LV/RV overlap. CpD and CpV with greatest width situated in the middle in both males and females ( Figs 11 E–F; 12E–F), without anterior rostrum.

Soft parts as typical of the genus, but generally more elongated than in the other species of Bennelongia . Hemipenes ( Fig. 13A, E ) symmetrical, edge of ms almost straight, ls with ventral extremity strongly pointed. Lpp ( Fig. 13B, F ) with distal segment narrow, tapering towards the point and rather long (the specimen in Fig. 13C is an exception). Rpp ( Fig. 13D, G ) with distal segment narrowly subtriangular, with apical margin straight, sensory organs on first segment unequal, one long, one short.

Etymology

The species is named after its most striking character, the triangular shape of the valves in lateral view.

Type material

Holotype

♂ ( WAMC55564 ), with soft parts dissected in a sealed slide and valves stored dry in a micropalaeontological slide.

Allotype

♀ ( WAMC55565 ), with valves stored dry in a micropalaeontological slide and soft parts used for molecular screening.

Paratypes

Numerous ♂♂ and ♀♀ from the type locality, either dissected and stored as the holotype, as carapaces used for SEM or in alcohol ( WAMC 55566–55573, OC3367–3369). See Table 1 for listing of specimens.

Other material investigated

Unnamed claypan, Gascoyne, WA (sample SIKE 11). Approximate coordinates: 24°47’49” S, 114°15’42” E. All material collected by the authors on 6 Jul. 2011. Several males and females (specimens WAMC 55576–55577). K25 = 434 µS/cm, Temp = 15.4°C, pH = 7.6.

Unnamed claypan, Muggon Station, Murchison, WA (sample SIKE 21). Approximate coordinates: 26°46’54” S, 115°40’53” E. All material collected by the authors on 8 Jul. 2011. Several males and females (specimens WAMC 55578–55583). K25 = 154 µS/cm, Temp = 13.3°C, pH = 8.0.

Homestead dam, Boolathana Station, Gascoyne, WA (sample ESKI /01). Approximate coordinates: 24°39’15” S, 113°41’37” E. All material collected by the authors on 5 Apr. 2013. Several females (specimens WAMC 55584).

Unnamed canegrass pan, Wooramel Stn, Gascoyne, WA (sample CB 35a). Approximate coordinates: 25°40’52” S, 114°13’14” E. Material collected by Stuart Halse on 24 Aug. 1994 (specimen OS 256).

Near Cardabia Swamp, Gascoyne, WA (sample CB 54). Approximate coordinates: 24°33’10” S, 113°45’35” E. Material collected by Stuart Halse on 18 Mar. 1995 (specimen OC3370).

Unnamed claypan, Doorawarrah Stn, Gascoyne, WA (sample CB 58b). Approximate coordinates: 24°48’8” S, 114°16’15” E. Material collected by Stuart Halse on 23 Aug. 1994 (specimen WAMC 55574).

Boolan Pool, Gascoyne, WA (sample CB 73). Approximate coordinates: 24°28’38” S, 113°40’36” E. All material collected by Stuart Halse on 18 Aug. 1994 (specimens OS 121, OS 391).

Cattle Camp Pan, Gascoyne, WA (sample CB 75a). Approximate coordinates: 24°28’25” S, 114°13’27” E. Material collected by Stuart Halse on 19 Aug. 1994 (specimen WAMC 55575).

Nicabay Flats, Gascoyne, WA. Approximate coordinates: 24°52’7” S, 113°43’3” E. Material collected by Stuart Halse on 15 Aug. 1995 (specimen OS 258).

Type locality

AUSTRALIA: Unnamed canegrass pan on Wooramel Station, Gascoyne, WA (samples CB35a and SIKE07). Approximate coordinates: 25°40’53” S, 114°13’17” E. All material collected by the authors on 5 Jul. 2011. K25 = 307 µS/cm, Temp = 15.5°C, pH = 7.4.

Measurements (all measurements in µm – see Table 1 for measurements of all specimens illustrated with SEM)

Holotype ♂ ( WAMC55564 ): RV: L = 1850, H = 1158; LV: L = 1923, H = 1188.

Allotype ♀ ( WAMC55565 ): RV: L = 2192, H = 1308; LV: L = 2286, H = 1350.

Differential diagnosis

This species is unlike any other species in the genus, because of the features cited in the diagnosis to the B. triangulata lineage, especially the large size, triangular shape and lack of an antero-ventral beak on the LV.

Remark

The species comes in two forms, one with valves high ( Figs 11 A–C; 12A–C) and one with valves more elongated ( Figs 11H, J ; 12H, J ). In the soft parts, both forms are almost identical, with the exception of the shape of the second segment of the Rpp. In the high form, this segment is subtriangular, with both dorsal and distal margins straight ( Fig. 13D ). In the more elongated form, this segment has a straight distal, but more sinuous dorsal margin ( Fig. 13G ).

Morphology, ecology and distribution

Bennelongia triangulata sp. nov. is common in the Murchison region north to the southern Pilbara region of WA and occurs in turbid claypans. As outlined above, the valve shape can be quite different (either rather high, or quite elongated), and originally it was thought that these two forms were either seasonally determined or constituted two species.

New sampling and screening of older collections showed that both forms occur in both summer and winter. Laboratory cultures reared at different temperatures, day length etc. may show which, if any, aspects of the environment may affect valve shape in this species. Males with different valve shape have slightly different morphologies in the Rpp, but as this could be part of a normal range of variability, its occurrence should be checked on longer series of dissections. Bennelongia timmsi Martens et al., 2013 also showed significant variability in the shape of the Rpp ( Martens et al. 2013).

Sadly, all specimens with elongated valves originated from old collections, on which no molecular work could be done. In spite of several attempts, we have not been able to collect fresh material of the elongated form. Future work will have to examine whether genetic data suggest that the two forms are different species. For the moment we retain both forms as being conspecific.

Figures

Fig. 11. Bennelongia triangulata sp. nov. (all ♀, A–G & K–M from type locality: canegrass pan on Wooramel Station, Murchison/Gascoyne, WA; H–J from CB54, Boolathana Station, Carnarvon Basin, WA). A. LVi (allotype, WAMC55565). B. CpRL (OC3368). C. RVi (WAMC55565). D. CpD, detail anterior margin (WAMC55569). E. CpD (WAMC55569). F. CpV (WAMC55570). G. CpV, detail anterior margin (WAMC55570). H. LVi (OC3370). I. LVi, detail posterior margin (OC3370). J. RVi (OC3370). K. RVi, detail anterior margin (WAMC55565). L. CpRL, detail anterior margin (OC3368). M. RVi, tilted, detail anterior margin (WAMC55565). Scales = 1 mm for A–C, E–F, H, J; 200 µm for D, G, I, K–M.

Fig. 12. Bennelongia triangulata sp. nov. (all ♂, A–G from type locality: canegrass pan on Wooramel Station, Murchison/Gascoyne, WA; H–M from CB54, Boolathana Station, Carnarvon Basin, WA). A. LVi (holotype, WAMC55564). B. CpRL (OC3369). C. RVi (WAMC55564). D. RVi, detail anterior margin (WAMC55564). E. CpD (WAMC55571). F. CpV (WAMC55572). G. RVi, tilted, detail anterior margin (WAMC55564). H. LVi (WAMC55574). I. RVi, tilted, detail anterior margin (WAMC55564). J. RVi (WAMC55574). K. LVi, detail central muscle scars (WAMC55574). L. RVi, detail anterior margin (WAMC55574). M. RVi, tilted, detail anterior margin (WAMC55574). Scale = 1 mm for A–C, E–F, H, J; 200 µm for D, G, I, K–M.

Fig. 13. Bennelongia triangulata sp. nov. (all ♂, A–D from CB75a, Cattle Camp Pan, Gascoyne, WA; E–G holotype (WAMC55564): cane grass pan on Wooramel Station, Murchison/Gascoyne, WA). A. Outline of hemipenis (WAMC55584). B. Lpp (WAMC55584). C. Lpp (WAMC55575). D. Rpp (WAMC55584). E. Outline of hemipenis. F. Lpp. F’. Lpp, detail of distal part of first segment. G. Rpp. Scale = 156 µm for A, E; 73 µm for B–D, F–G.