Paroster baylyi sp. n. Type locality: Bilya Rock, 25 km NNW Morawa, Western Australia, ca. 28.98S 115.87E {1}. Type material: Holotype: Male: “ 25 km NNW Morawa, Mullewa—Wubin Road, “Bilya Rock”, 6.9.2002, 28°59′S 115°52′E Hendrich leg. loc. WA 22/186” [white, printed]; “ HOLOTYPE Paroster baylyi sp. n. Hendrich & Fery des. 2007” [red, printed] {1} (WAM). Paratypes: 71 exs., same locality data as the holotype (CLH, CHF, NMW, SAMA, WAM, ZSM); 14 exs., “ 31 km E Perenjori, “Camel Soak”, 7.9.2002, 29°22′S 116°38′E Hendrich leg. loc. WA 24/188” [white, printed] {2} (CLH, SAMA); 6 exs., “Midwest, 10 km E Wubin, Gunjidi—Wubin Road, rock-pools, 7.9.2002, 30°08′S 116°31′E Hendrich leg. loc. WA 26/190” [white, printed] {3} (CLH, SAMA). All paratypes are provided with a red printed paratype label. Description: Habitus and size: Body oval and vaulted; elytra widest near or shortly behind middle; in dorsal view with weak discontinuity in outline between pronotum and elytra (Figs 2, 3). Measurements: holotype: TL: 3.65 mm, TL-H: 3.45 mm, MW: 2.05 mm, TL/MW: 1.78, TL-H/MW: 1.68; paratypes: males (n = 15): TL: 3.4–3.9 mm (3.66 ± 0.15 mm), TL-H: 3.1–3.6 mm (3.39 ± 0.14 mm), MW: 1.8–2.1 mm (1.93 ± 0.09 mm), TL/MW: 1.78–2.00 (1.89 ± 0.06), TL-H/MW: 1.63–1.84 (1.76 ± 0.06); females (n = 15): TL: 3.25–3.7 mm (3.49 ± 0.13 mm), TL-H: 2.9–3.35 mm (3.18 ± 0.13 mm), MW: 1.7–2.0 mm (1.86 ± 0.07 mm), TL/MW: 1.80–1.95 (1.87 ± 0.04), TL-H/MW: 1.65–1.78 (1.71 ± 0.03). Colour: Head dark reddish brown, clypeus anteriorly and near eyes yellowish; pronotum yellowish, base medially dark brown, disc diffusely brownish in variable extent; anterior margin often darker since dark vertex of head shining through. Elytra reddish brown with expanded and diffusely limited yellowish basal, lateral and apical markings; also lighter brownish along suture. Underside lighter reddish brown, sides of metacoxal plates, metasternum and parts of abdominal segment diffusely darkened. Legs and head appendages also lighter reddish brown, antennomeres beginning with fourth progressively darkened apically. Structure: Head with anterior margin slightly truncate; behind anterior margin with two clypeal grooves. Pronotum in dorsal view with sides anteriorly strongly curved, behind almost straight and diverging; point of maximum width at base; margin with thin and weak rim. Elytra in dorsal view with sides more or less evenly rounded, short before apex more curved. Underside with prosternal process lanceolate, variable in shape, from tectiform to carinate in cross section, and sharply pointed to shortly rounded posteriorly; always reaching metasternum. Metacoxal lines subparallel, slightly diverging anteriorly, not reaching hind margin of metacoxal plates; distance between lines relatively large; midline groove reaching metacoxal plates, stronger impressed in anterior third. Epipleura broad in anterior fourth, distinctly narrowed at level of first ventrite; each epipleuron near shoulder crossed by an oblique weak carina, ending just before elytral margin. Inner face of each elytron preapically provided with a narrow and thin, but well perceptible costa (ligula), and this in contrast to statements given in Pederzani (1995: 35). First and second antennomere longer than third, fourth shorter than third and fifth; fifth to eleventh segment distinctly flattened. Last segment of labial palpus truncate and notched apically. Surface-sculpture: Entire upper surface distinctly reticulate with small almost round meshes of more or less equal diameter. Head with reticulation somewhat stronger impressed; punctation sparse, fine and simple, punctures of same diameter as meshes. Punctures on pronotal disc similar, denser and coarser near sides, behind anterior margin very coarse and strongly impressed. Elytral punctures larger and denser than on head and disc of pronotum; diameter equal to that of two or three meshes, distance between punctures about three times that of their diameter. Puncture lines on elytra distinct. Setation on surface erect, but very sparse, restricted mainly to puncture lines and sides of elytra; in some specimens also sides of pronotum with a few setae. Underside with weak to moderate microreticulation, meshes elongate, except on interspace of metacoxal lines; here meshes almost round and more strongly impressed; punctation weak and shallow. Epipleura with reticulation as on elytra, practically without any punctation. Meso- and metafemora with two lines of coarse punctures, one along midline, second one along anterior margin; profemur with similar lines, but second one along posterior margin. Protibia along midline with a row of deeply impressed punctures, apically with similar additional coarse punctures; punctures on mesotibia more coarse and irregularly distributed. Setation on underside very sparse, short and almost imperceptible, only in punctures near posterior margins of third to fifth ventrites longer, and centres of second to fourth ventrites each with several very long hairs. Variability: Mainly concerning colouration: darker areas on surface variable in extent, however never reaching base; in several specimens elytra with dark areas weakly lightened centrally. Male: Pronotum and elytra shiny due to weaker impressed reticulation. First three pro- and mesotarsomeres moderately strongly expanded; first tarsomeres of pro- and mesotarsi apically with two large suction cups (Figs 20, 21); anterior protarsal claw distinctly thickened, curved and twisted apically, slightly longer than posterior claw; latter thinner and less curved at tip. Length of anterior claw approximately equal to that of fifth tarsomere. Median lobe of aedeagus as in Fig. 9, on dorsal side with a weak carina (length ca. 0.2 mm) before apex; left paramere as in Fig. 12. Apex of parameres with very few very short setae. In several speci-mens—but not in all—left paramere indistinctly broader than right one. Female: On average smaller than males (see Measurements). Elytra matt, owing to stronger impressed reticulation of dorsal surface; punctation less prominent. Pronotum also with stronger reticulation, at least on sides, however differences to males less apparent and still shiny. Pro- and mesotarsomeres quite strongly expanded, but less so than in males; first tarsomeres without suction cups; protarsal claws simple. Gonocoxae as in Fig. 15, gonocoxosternum as in Fig. 18. Etymology: Dedicated to Prof. Ian Bayly for his fascinating contributions to the knowledge of granite outcrops in Australia. Distribution: Inland of south-western Australia. Northwest of a line from Perth to Cue (Fig. 22). Habitat: All specimens were obtained from exposed, small (1–2 m ²), shallow (up to 20 cm depth) and ephemeral pools on granite outcrops (pan-gnammas) by using a small net and a kitchen strainer. Bottom consisting of sand of bare rock and stones with a thin layer of rotten debris (Figs 25–28).

Published as part of Hendrich, Lars & Fery, Hans, 2008, Paroster baylyi sp. n., P. ursulae sp. n. (Col. Dytiscidae, Hydroporinae) and the water beetle diversity of pan-gnammas on isolated granite outcrops in the Mallee of south-western Australia, pp. 27-41 in Zootaxa 1704 on pages 33-35, DOI: 10.5281/zenodo.180850