Carabhydrus innae, 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 : 10-11

Carabhydrus innae sp.n.

( Figs 2 , 12, 13, 14, 15 , 29 , 34, 35 )

Type locality: Wentworth River , Victoria, Australia .

Type material: Holotype: Male: “Wentworth Riv. Vic. 30-12-1975 Site 1A [WR1A, 37°34´S 147°22´E, 2.8. km upstream from Tabberabbera , about 40 m upstream from the Tabberabbera-Bullumwaal Road bridge] Sample 5. Mitchell River Survey Nat. Mus. Vic.”, “ Holotype Carabhydrus innae sp. n. Hendrich & Watts des. 2008” [red printed label] ( NMV) . Paratypes: 1 female, “VIC Jn of Thomson & Aberfeldy Rivers Fingerboard Spur Tk 4/v/1977 N.M.V. Survey Dept G.R.E.S T20 no2”, “ Carabhydrus andreas Zwick det R.E. Roughley 1986”, “SAMA Database 25–003776” ; 1 male, “ Never Never Creek , Promised Land, NSW, Aust. 9 Dec 2002 A. Glaister ”, ( SAMA) ; 2 males, 1 female, “NSW Clyde River, Clyde Ridge Rd [Road] 13.5.99 Riffle, Syd. Water Board” ( SAMA, CLH). All paratypes are provided with a red printed paratype label .

Description: Measurements: Holotype: TL = 3.4 mm, TL-H = 3.05 mm, MW = 1.4 mm. Paratypes: TL = 3.1–3.6 mm, TL-H = 2.8–3.3 mm, MW = 1.25–1.4 mm.

Color ( Fig. 2 ): Almost reddish-brown, clypeus, antennae, palpi and legs dark reddish brown. Two large basal elytral marks covering on third of elytra and extending to sides and suture, and two large apical spots of elytra pale reddish brown. Ventral surface reddish brown first two abdominal segments darker.

Sculpture: Head anterior to dorsal impression with deep punctures separated by a distance about 1 ½ equal to their own diameters, and a few sparse, minute punctures; interspaces smooth and shiny, densely and very coarsely punctuate and microreticulate along hind edge and along hind edge on a strip along the large eyes, and in two shallow depressions medially from indistinct swellings above the antennae.

Pronotum shining, finely and very sparsely punctuate at disc, very dense with larger punctures on rest of surface, strongest between striae and on basal part, forming deeper grooves, microreticulation absent.

Elytron with dual irregular punctation similar to that of pronotum but more dense, surface somewhat uneven especially near middle where punctures are larger, near tip they are fine. Smaller punctures at apical third of elytra very sparsely and hardly visible. Epipleura simple, distally narrowed, disappears in distal fourth with dense, more or less contiguous punctures.

Ventral surface with punctures similar in than those of dorsal surface, denser and more irregular with surfaces of sclerites irregularly rugose; punctures of metacoxal plate and sterna 1 and 2 not evidently larger than those elsewhere on ventral surface; metasternum medially and metacoxa between metacoxal lines coarsely and sparsely punctate. Legs with femora, tibiae, and dorsal surface of metatarsomeres 1–3 strongly punctate.

Structure: Head very broad, with deep and broad cervical stria between posterior edge of 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 eyes; maxillary and labial palpi each with apical palpomere fusiform.

Pronotum not transverse, almost parallel sided, base distinctly broader than head, widest just behind middle. Basal half flat, anterior part curved down. Lateral margin in dorsal aspect more or less evenly rounded; lateral bead sharply defined, narrow; basal margin slightly lobed medially; disc with a pair of broad and deep longitudinal impressions, each extending from apical third of disc to hind margin and strongly limited on outer side by a more or less carinate ridge, one large deep depression just behind centre of pronotum and of same size and form as longitudinal impressions, mesal margin less distinct; several additional shorter and more irregular rugae or impressions as well as coarse elongate punctures along basal margin adjacent to the major impressions. Scutellum visible, short and broad.

Elytra together elongate-oval with point of maximum width in apical third, 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, lateral portions of thorax and abdomen narrowed ventrally, medially forming a more or less flattened area comprising prosternal process, medial area of metasternum, intralinear space of metacoxae, and abdominal sterna medially. Prosternum with anterolateral pore well removed from anterior margin. Prosternum and its process in lateral aspect in almost same plane; process hardly deflexed, grooved in middle, sides raised, oval. Metasternum largely in a vertical plane, prosternal process touches metasternum between mesocoxae. Metasternum medially flat, faintly raised anteriorly joined lines extend from between mesocoxal plates posteriorly, where they become indistinct. Metacoxal lines strongly raised, first directed a little outward as usual but their front ends curved medially. Metacoxal process flat, distally hardly sinuous, indistinctly notched in middle. Legs very long. 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 1–6 twice as long as wide; 7–10 slightly and progressively widened 1.5 time as long as wide, 11 fusiform. Profemur with anteroventral margin bearing a short medial, stout spines. Protibia enlarged anteriorly with mesal margin bearing a subapical tooth and a basal row of short, pale setae. Protarsomeres 1–3 slightly dilated, last tarsal segment without claws same length as second or third segment. Mesofemur slightly enlarged posteriorly. Mesotibia without subapical tooth. First mesotarsal segment enlarged, forming a triangular hook ( Fig. 15 ), last tarsal segment without claws as long as second and third segment. Parameres sclerotized, broad, symmetrical, almost triangular and typical “ Hydroporinae shaped”, as long as aedeagus; median lobe of aedeagus ( Figs 11, 12 ) in ventral aspect with apex bilobed, broadly emarginate medially, with two sets of lateral flanges and an apical medial ridge.

Female: Females are a bit smaller than males. Measurements: TL = 3.1–3.35 mm, TL-H = 2.8–2.9 mm, MW = 1.3–1.4 mm.

Differential diagnosis: A very distinct species which can be easily separated from all other species of the genus by its size, with a total length of 3.1–3.6 mm by far the largest species of the genus, more parallel sided pronotum, large deep depression in the centre of pronotum, flattened body with sutural region depressed, and the pale characteristic maculate elytra ( Fig. 2 ). Furthermore, C. innae sp.n. differs from all other species of the genus by the form of the median lobe ( Figs 12, 13 ), shape of the parameres ( Fig. 14 ), and the strong triangular hook-like form of the first mesotarsal segment in the male ( Fig. 15 ).

Etymology: The species is dedicated to Dr Inna Borodavko, the mother in law of the senior author.

Distribution: Southern Victoria and New South Wales ( Fig. 29 ).

Habitat: A rheophilic species collected from rivers and creeks with riffle habitats, and with both cobble and boulder substratum and fringed by forest. According to an unpublished report from 1976, deposited in the Victorian Museum in Melbourne, the Wentworth River bed at this site…“is approximately 10–15 m wide. Dry sclerophyll forest predominates on steep surrounding slopes, whilst the land adjacent to the river suggests that after clearing, uncontrolled regrowth was permitted. Soil erosion and fire damage are evident. Along the river banks tussock vegetation is interspersed with thickets of burgan ( Leptospermum phylicoides ), tall grass and blackberry. Substratum is largely loose and made up of pebbles and cobbles on gravel. Current varies from slow to fast, and depth from 10 to 30 cm in autumn, to 40 to 60 cm in spring. Flow comparatively laminar”. An intensive survey by the senior author at the second locality at junction of the Thomson and Abberfeldy Rivers ( Figs 34, 35 ) in November 2006 revealed no further specimens.

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 10–19. Median lobe of aedeagus in ventral and lateral view (scale bar 0.2 mm): 10, 11—Carabhydrus andreas and 12, 13—C. innae sp.n.; 14, 15—C. innae sp.n. right paramere (14) and first two mesotarsal segments (15) in dorsal view (scale bar 0.2 mm). Median lobe of aedeagus in ventral and lateral view: 16, 17—C. janmillerae sp.n. and 18,19—C. monteithi.

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

FIGURES 30–35. Habitats of 30,31—C. andreas, Gibraltar Falls, downstream and upstream (ACT), November 2006; 32—C. niger, NW Tasmania, Detention River, 2.5 km SW Mawbanna, December 2006; 33—C. niger, 13 km NNW Dungog, Williams River, Tillegra Bridge, October 2006; 34, 35—C. innae sp.n., Thomson River in Baw Baw National Park (Victoria) (Photos L. Hendrich).