Bennelongia frumenta sp. nov.

(Figs 10-11)

Etymology

Bennelongia frumenta sp. nov. is typical of the south-western side of the Western Australian wheatbelt. Wheat = frumenta in Latin.

Diagnosis

Valves triangular in lateral view, weakly pitted, width more than half the length in dorsal / ventral view and with rostrum well-developed. LV with beak weakly developed. RV with lapel triangular, ventrally pointed; selvage near lapel with a cavity, visible with SEM, but especially with transparent light. Hemipenis with ls slightly extending beyond ms, ls distally rounded and with bluntly pointed apex; ms ventrally and dorsally without lobe-like expansion. Rpp with trapezoidal distal segment; with nearly straight distal margin and very narrow base. Lpp with distal segment sickle-shaped, elongated, almost as long as first segment.

Measurements (all measurements in µm)

Male: RV: L = 1310; H = 907. LV: L = 1430; H = 933. Cp: L = 1320-1330; H = 841; W = 810-826. Female: RV: L = 1320-1390; H = 851-905. LB: L = 1460-1500; H = 962. Cp: L = 1400-1520; H = 878; W = 901-907.

Type locality

Kodjinup Melaleuca Swamp, 6 km N of Lake Muir in the Cranbrook shire (WA), collected by Adrian Pinder and Jane McRae on 2 Oct. 1998, approximate coordinates; 34 º 23’ 45”S 116 º 39’ 1”E (OSTR11A, SPS105).

Type material

Holotype

Female (WAM.C49380), with soft parts dissected in a sealed slide and valves stored dry in a micropalaeontological slide.

Allotype

Male (WAM.C49381), with soft parts dissected in a sealed slide, valves kept in EtOH (decalcified).

Paratypes

LV+ RV of a female (OC.3312); one female carapace (WAM.C49383); three male carapaces (WAM. C49382A-C); soft parts of one male (WAM.C49384 – valves lost).

Several in toto specimens in EtOH (voucher specimens WAM.C49385).

Other material investigated

Wetland south east of Kodjinup Swamp, collected by Andrew Storey and SH on 21 Oct. 1997, approximate coordinates: 34º 23’ 00”S 116º 40’ 00”E. Specimens from this locality: a dissected male (WAM.C49386); LV+ RV of a female (WAM.C49387).

Job’s Sump, collected by Jane McRae and Mick Smith on 10 Oct. 1997, approximate coordinates: 32º 21’ 15”S 117º 39’ 27”E (SPS 060).

West Kulunilup Swamp, collected by Andrew Storey and SH on 22 Oct. 1997, approximate coordinates: 34º 20’ 00”S 116º 47’ 00”E. Specimens from this locality: several voucher specimens in EtOH (OSTR 13E), slide #38, a dissected male (OC.3313) and a female CP (WAM.C49388).

Unnamed claypan, Pingrup, collected by Adrian Pinder on 13 Sep. 2007, approximate coordinates: 33º 26’ 49”S 118º 30’ 41”E. Specimens from this locality: several voucher specimens in EtOH (OSTR 13G, ABP 051); LV+ RV of a female (OC.3314).

Lake Wheatfield, collected by David Cale on 26 Oct. 2005, approximate coordinates: 33º 48’ 46”S 121º 55’ 38”E (SPM 005B).

Differential diagnosis

Bennelongia frumenta sp. nov. belongs to the B. cygnus lineage because of its triangular shape, the simple type of hemipenis and the pointed lapel. It can be distinguished from the other species in this lineage, B. cygnus sp. nov. (see above), by the presence of a cavity in the selvage near the lapel, the absence of a dorsal lobe on the ms of the hemipenes, the elongated second segment of the Lpp and the narrow base of the second segment of the Rpp.

Additional description

Valves triangular (Figure 10 A-D), with greatest height situated in the middle; LV overlapping RV on all sides (Figure 10K), dorsally only in the first half of the carapace, ventral margin almost straight; width of carapace in dorsal and ventral views (Figure 10 E-H) more than half the length, greatest width situated in the middle, anterior rostrum strong; carapace weakly pitted and set with few, very short setae.

Male valves slightly smaller and more highly arched than female valves, otherwise very similar in appearance.

LV (Figure 10A, C) with posterior calcified inner lamella narrow, inner list running along valve margin and creating a narrow sulcus; this sulcus continuing towards the anterior side and widening up in between both anterior inner lists; antero-ventral beak weakly developed.

RV (Figure 10B, D) of similar shape as LV, smaller and slightly less high; posterior and ventral margin set with tubercles, anterior calcified inner lamella with short inner list, the latter forming a ‘cavity’ in and on the selvage near the lapel; lapel relatively long, rather ventrally situated and ventrally pointed (Figure 10I, J); inner margin of posterior calcified inner lamella with long inner list (reaching almost up to dorsal margin) and with selvage submarginal.

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

Rpp (Figure 11B) with basal segment elongated, c. 1.5 x the central width; subapically with two unequal sensory organs; second segment trapezoidal, with blunt dorsal and pointed ventral edge, distal margin nearly straight, base of segment very narrow.

Lpp (Figure 11C, D) with first segment more slender, more than twice as long as wide, subapically with an elongated outgrowth, subapically with a short sensory organ; distal segment sickle-shaped and elongated, longer than dorsal margin of first segment.

Walking leg (Figure 11E) stout and hirsute.

Hemipenes (Figure 11A) symmetrical; LS with rounded dorsal margin and bluntly pointed distal edge; MS with oblique but straight distal margin, ventrally with a broadly rounded lobe, ventrally without additional lobe.

Ecology and distribution

The species has thus far been found in a variety of seasonal and, less commonly, permanent wetlands and streams in the south-western Wheatbelt of Western Australia and in higher rainfall areas. The species has been recorded in water with conductivity 1550-9260 µS cm-1 and pH 6.0-9.6.