Carabhydrus storeyi, Hendrich & Watts, 2009

Hendrich, Lars & Watts, Chris H. S., 2009, Taxonomic revision of the Australian predaceous water beetle genus Carabhydrus Watts, 1978 (Col. Dytiscidae, Hydroporinae, Hydroporini), Zootaxa 2048 (1), pp. 1-30 : 22-23

Carabhydrus storeyi sp.n.

( Figs 4 , 26, 27 , 28 , 38, 39 )

Type locality: Mary River , at Maryfarms, NE Queensland, Australia .

Type material: Holotype: Male: “Mary R. [ Mary River ] at Mary Farms [Maryfarms] Qld.16´34´07´´S 145´11´32´´E Dept. Nat. Resources Qld 19/12/97”, “SAMA Database No. 25-00 4256”, “ Holotype Carabhydrus storeyi sp. n. Hendrich & Watts des. 2008” [red printed label] ( SAMA) . Paratypes: 1 male and 2 females with same data as holotype ( CLH, SAMA). All paratypes are provided with a red printed paratype label .

Description: Measurements: Holotype: TL = 1.7 mm, TL-H = 1.5 mm, MW = 0.7 mm. Paratypes: TL = 1.65–1.75 mm, TL-H = 1.5–1.55 mm, MW = 0.65–0.75 mm.

Color ( Fig. 4 ): Dorsal side testaceous to light reddish brown, elytra with large testaceous basal marking, ventral surface of head and thorax, and basal and apical margins of sterna 4–6, dark brown. Antenna, palpi and legs pale yellowish brown, without infuscation.

Sculpture: Head anterior to dorsal impression with minute punctures separated by a distance about four times to their own diameters, and a very few sparse lager punctures; interspaces smooth and shiny without microreticulation except frontal foveae coarsely reticulate and anterior margin of clypeus with transverse lines; head posterior to transverse impression with few coarse punctures medially and laterally posteriad to eyes, remainder of space impunctate but with reticulate sculpture.

Pronotum with smaller but deeper punctures separated by a distance about three times to their own diameters; disc anterolaterally at base of front angle rugose with several coarse setiferous punctures; microreticulation absent.

Elytron with larger and deeper punctation more dense; interspaces smooth microreticulation in both sexes absent; epipleuron with dense, more or less contiguous punctures.

Ventral surface with punctures similar in size than those of dorsal elytral surface, denser and more irregular with surfaces of sclerites irregularly rugose; punctures of metacoxal plate, metasternum medially and metacoxa between metacoxal lines and sterna 1 and 2 evidently larger than those elsewhere on ventral surface; sparsely and finely punctate. Legs with femora, tibiae, and dorsal surface of metatarsomeres 1–3 strongly punctate.

Structure: Head broad, with small eyes, lateral margins of clypeus somewhat produced laterally above base of antenna; frontal fovea distinct, ovate; dorsal surface with a strong transverse impression between posterior margins of small eyes; maxillary and labial palpi each with apical palpomere fusiform.

Pronotum in dorsal aspect slightly cordiform with point of maximum width at about half of length, lateral margin in dorsal aspect more or less evenly rounded except shortly sinuate before obtuse posterolateral angle; disc with a pair of longitudinal impressions, each extending from convex mediolateral portion of disc almost to hind margin and strongly limited on outer side by a more or less carinate ridge, mesal margin less distinct; all specimens with one to several additional shorter and more irregular rugae or impressions as well as few elongate punctures along basal margin adjacent to the major impressions. Scutellum visible, but very short and broad.

Elytra together elongate-oval with point of maximum width near middle, sides converging basally; disc of each elytron with a medial and a sublateral, broad, longitudinal groove each bearing a row of serial punctures, and a less evidently defined lateral groove adjacent to lateral margin; medial and sublateral groove beginning approximately opposite basolateral impression of pronotum, sharply defined on basal three-fourths, becoming shallower apically. Ventral surface as in C. andreas but legs relatively large. Coxae and trochanters normal. Femora simple, metafemur shorter than others and much shorter than tibia. All femora largely visible from above. Profemur and protibia as in C. andreas . Mesotibia straight, inner face with few long hairs. Pro- and mesotarsomeres 1–3 ovate; protarsomere 4 small, situated within emargination of tarsomere 3 but visible in dorsal aspect. Hind legs slender; metatibia straight, evenly broadened from base to apex, natatorial setae absent from ventral face in both sexes; metatarsal claws equal.

Male: Antenna only slightly broadened, antennomeres 5–7 very slightly and progressively widened, 8–10 about as wide as long, and 11 fusiform. Protibia and inner margin of mesotibia without obtuse, subapical tooth. Protarsomeres 1–3 slightly dilated, tarsomere 1 with a pair of large oval scales in addition to numerous small adhesive setae. Paramere sclerotized, broad, ovate, very much shorter than aedeagus; aedeagus ( Figs 26, 27 ) in ventral aspect slender and narrow medially and anteriorly, apex strongly tapered.

Female: Females are a bit smaller than males. Measurements: TL = 1.65 mm, TL-H = 1.5 mm, MW = 0.65 mm.

Differential diagnosis: A very distinct species which can be easily separated from all other species of the genus by its small size, the characteristic colouration of the elytra ( Fig. 4 ) and the very strange form of the median lobe ( Figs 26, 27 ).

Etymology: This species is dedicated to the late Ross I. Storey, entomologist and curator at Queensland Department of Primary Industries, Mareeba, Queensland.

Distribution: North-eastern Queensland ( Fig. 28 ). Only known from the type locality.

Habitat: A rheophilic species. The Mary River at Maryfarms is normally a low gradient, shallow river, 3–6 meters wide, flowing through fringing rain forest with a substrate of clean sand with areas of dead leaves and fine detritus ( Figs 38, 39 ). Several small tributaries 1–2 meters wide and faster flowing enter the main river nearby. It is unknown just where the specimens were collected from.

Figures

FIGURES 1–4. Habitus of Carabhydrus. 1—Carabhydrus andreas (male); 2—C. innae sp.n. (holotype, male); 3—C. plicatus; 4—C. storeyi sp.n. (paratype, male) (scale bar 1 mm) (Photos: L. Hendrich).

FIGURES 20–27. Median lobe of aedeagus in ventral and lateral view (scale bar 0.2 mm): 20, 21–Carabhydrus mubboonus; 22, 23—C. niger; 24, 25—C. plicatus; 26, 27—C. storeyi sp.n.

FIGURES 28–29. Distribution of the genus Carabhydrus in Australia.

FIGURES 36–39. Type localities of 36, 37—C. turaki sp.n., head waters of Pappinbarra River, Werrikimbe National Park in New South Wales (Photos: Natacha Waddell, April and October 1995); 38, 39—C. storeyi sp.n., Mary Creek at Maryfarms NE Queensland (Photos: C. Watts, December 2008).