Carabhydrus stephanieae Watts, Hancock & Leys 2007

(Figs 6, 29)

Carabhydrus stephanieae Watts, Hancock & Leys 2007: 56.

Type locality: Groundwater bore, 17.4 km east of Scone, Pages River, Hunter Valley, New South Wales, Australia.

Type material: Holotype: Female: “Department Natural resources monitoring bore n. 80439 (32°02´57´´S, 150°56´35´´E), 17.4 km east of Scone, NSW. P. Hancock 3.iv.2005 ”; “ HOLOTYPE Carabhydrus stephanieae Watts et al. 2007 ” [red printed label] (SAMA). Paratypes: 4 females: 1 with same data as holotype, slide mounted (SAMA); 2 same data as holotype except “bore n. 80437 (32°03´00´´S, 150°49´06´´E), 4.vii.2005 ” (SAMA). All paratypes are provided with blue printed paratype labels.

Re-description: Measurements: TL = 2.10–2.50 mm, TL-H = 1.95–2.20 mm, MW = 1.00– 1.10 mm.

A detailed description of the first stygobitic species of the genus is given in Watts et al. (2007). The male is still unknown.

Notes: Unlike most other Australian stygobitic Dytiscidae, whose realtionships were initially uncertain, C. stephanieae is clearly a member of the Hydroporinae genus Carabhydrus and retains the general body shape, exposed scutellum and even traces of elytral grooves characteristic of that genus. This placement was confirmed by a molecular analysis (Watts et al. 2007). The only clearly stygal features are the lack of eyes, although the uniform, but still strong, colour, and reduction of elytral ridges (Watts et al. 2007) are sugestive of a stygobitic existance.

Differential diagnosis: The uniformly pale testaceous colour, flat body, broad pronotum which is as wide as elytra in middle, and the eye remnants reduced to short sutures, distinguish this species from all other species of the genus (Fig. 6).

Distribution: Tributaries of Hunter River in eastern New South Wales (Fig. 29).

Habitat: All specimens were collected from two groundwater-monitoring bore holes, at depths of 11 to 13 m, from alluvial aquifers associated with two tributaries of the Hunter River near Scone. At all localities, sampling consisted of 10 hauls of a weighted (63 µm mesh) net followed by the filtering (through 63 µm mesh) of 300 litres of pumped water (Waterra Power Pump II, Enviroequip, Sydney). Both the net and the pump succeeded in collecting beetles, indicating that they were living in both the bore casing and the surrounding aquifer (Watts et al. 2007).