Bennelongia cygnus Martens & Schön 2012, sp. nov.
Creators: name: Martens, Koen
name: Halse, Stuart
name: Schön, Isa
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Ostracoda
Podocopida
Cyprididae
Bennelongia
Bennelongia cygnus

description: Bennelongia cygnus sp. nov.
(Figs 5-9)
Bennelongia sp. – Davies & Christidis, 1997: 82, fig. 8.3.22.
Etymology
The type locality of this new species is situated in the Swan Valley near Perth. We thus name this species after the (black) swan, Cygnus in Latin.
Diagnosis
Valves triangular in lateral view, weakly pitted, relatively narrow in dorsal view and with rostrum weakly developed. LV with beak weakly developed. RV with lapel long and narrow, ventrally tear-like, almost pointed. Hemipenis with ls extending beyond ms, ls distally rounded and with bluntly pointed apex. ms dorsally with additional lobe-like expansion. Lpp with distal segment sickle-shaped, but relatively short. Rpp with sub-trapezoidal distal segment.
Measurements (all measurements in µm)
Male: RV: L = 1330; H = 933-954. LV: L = 1330-1410; H = 968-969.
Female: RV: L = 1450-1600; H = 1000-1070. LV: L = 1550-1750; H = 1030-1130. Cp: L = 1690-1790; W = 1120-1130; H = 1100.
Type locality
Ellen Brook Nature Reserve, Swan Valley, near Perth (WA); approximate coordinates: 31º 44’ 00”S 116º 01’ 00”E. Material used for the present description was collected on 25 Sep. 1991, 3 Oct. 1997 and 2 Oct. 1998, all by SH.
Type material
Holotype
Male (WAM.C49370), with soft parts dissected in a sealed slide and valves stored dry in a micropalaeontological slide.
Allotype
Female (WAM.C49371), with soft parts dissected in a sealed slide, and valves stored dry in a micropalaeontological slide.
Paratypes
Five males dissected and stored as the holotype (WAM.C49372-49375, OC.3310); RV + LV of one female (OC.3311).
Several in toto specimens in EtOH (voucher specimens WAM.C49376).
Other material investigated
Perth Airport unnamed swamp, collected by SH on 12 Sep. 1995, approximate coordinates: 31º 56’ 00”S 115º 58’ 00”E
Goonaping Swamp, collected by Adrian Pinder and Jane McRae on 3 Oct. 1997, approximate coordinates: 32º 27’ 46”S 119º 25’ 1”E. (illustrated specimens from this locality: RV + LV of a female (WAM.C49377); two female carapaces (WAM.C49378) all from OST11C).
Christopher Brook, collected by Adrian Pinder and Jane McRae on 28 Oct. 1997, approximate coordinates: 32º 10’ 12”S 116º 47’ 39”E. (illustrated specimens from this locality: RV + LV of a female (WAM.C49379) from OST11A).
Cobertup Swamp, collected by Andrew Storey and SH on 19 Oct. 1996, approximate coordinates: 34º 27’ 00”S 116º 49’ 00”E.
One Tree Hill, collected by SH and Adrian Pinder on 11 Aug. 1999, approximate coordinates: 29º 35’ 19”S 115º 26’ 31”E.
Differential diagnosis
Bennelongia cygnus sp. nov. defines the B. cygnus lineage by its triangular shape, the simple type of hemipensis and the pointed lapel. It can be distinguished from the other species in this lineage, B. frumenta sp. nov. (see below), by the absence of a cavity in the selvage near the lapel, the presence of a dorsal lobe on the ms of the hemipenes, the short second segment of the Lpp and the broad base of the second segment of the Rpp.
Additional descriptions
Male valves (Figure 5C, D) slightly smaller and more highly arched than female valves (Figure 5A, B, H), otherwise very similar in appearance. Both valves triangular, with greatest height situated in the middle of the valves, dorsal margins equally sloping to both anterior and posterior margins, ventral margin almost straight. Valves weakly pitted and set with few, very short setae.
LV (Figure 5A, C) with posterior calcified lamella narrow, inner list running along valve margin and creating a narrow sulcus; the latter continuing towards the anterior side and widening up in between both inner lists (see diagnosis of genus); antero-ventral beak weakly developed.
RV (Figure 5B, D, H) of similar shape as LV, smaller and slightly less high; posterior and ventral margin set with tubercles, anterior calcified lamella with short inner list; lapel relatively long, rather ventrally situated and tear-shaped at its ventral edge (Figure 5I, J); posterior side with long inner list (reaching almost up to dorsal margin) and with selvage clearly inwardly displaced.
Width of carapace in dorsal (Figure 5E) and ventral (Figure 5F) views more than half the length, greatest width situated in the middle, LV overlapping RV on all sides, especially anteriorly and posteriorly (Figure 5), anterior rostrum very weakly built, to almost absent.
A1 (Figure 6E) with all segments relatively short and narrow, natatory setae long, chaetotaxy as typical of the family.
A2 (Figure 6A, C) with 5 natatory setae extending beyond tips of end claws, basic chaetotaxy and sexual dimorphism in chaetotaxy of penultimate segment as typical of the family: in female with claws G1-G3 and z1-3 setae; in males with G1 a short claw, G2 a large claw and G3 a seta of intermediate length; z1 and z2 large claws, z3 a long seta.
Md coxa (Figure 7A) relatively slender, without special features. Mandibular palp (Figure 7 B-D, G) with chaetotaxy as typical of the family, endclaws and gamma seta unusually slender.
Mx1 (Figure 7E, F) with second palp segment rectangular, c. twice as long as basal width, 3 claws of this segment relatively slender. Third endite with smooth ‘zahnborsten’. Sideways directed bristles on first endite of unequal length.
T1 (Figure 8 C-E) with endite bearing 16, mostly hirsute, setae of unequal length. Females with endopod a palp bearing 3 unequal apical setae. Males with endepod developed in asymmetrical prehensile palps. Rpp (Figures 8D, 9C) with basal segment stout and only slightly longer than the largest width, subapically with two unequal sensory organs; second segment trapezioidal, with blunt dorsal and pointed ventral edge. Lpp (Figures 8C, 9D) with first segment more slender, almost twice as long as wide, distal segment sickle-shaped but relatively short (L = <half L of first segment).
T2 (Figure 6B) a walking leg with seta d1> d2.
T3 (Figure 6D) a cleaning limb.
CR (Figure 9E) and its attachment (Figure 9F) slender.
Hemipenes (Figures 8A, B; 9A, B) almost symmetrical, with ls slender, with rounded dorsal margin and bluntly pointed distal edge; ms consisting of two sub-lobes, one rectangular, the second one elongated and ventrally directed, with rounded edge.
Ecology and distribution
The species appears to be comparatively widespread in freshwater bodies in south-western parts of Western Australia. The species was found in clear or darkly coloured water with conductivity ranging from 80-3120 µS cm-1 and pH 6.8-8.5.
Remarks
One male specimen (WAM.C49375 – Figure 9A, B) had aberrant morphology of hemipenes and Rpp. The hemipenes were asymmetrical, with one being typical of the species, the other bearing an additional thumb-like expansion of the ls. The same specimen also had an additional distal thumb-like expansion of the second segment of the Rpp. Rather than considering this a different species, we decided that it is most likely a teratological specimen.
description: Published as part of Martens, Koen, Halse, Stuart & Schön, Isa, 2012, Nine new species of Bennelongia De Deckker & McKenzie, 1981 (Crustacea, Ostracoda) from Western Australia, with the description of a new subfamily, pp. 1-56 in European Journal of Taxonomy 8 on pages 13-20, DOI: 10.5852/ejt.2012.8, http://zenodo.org/record/3857965