Carabhydrus janmillerae, 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 : 12-13

Carabhydrus janmillerae sp.n.

( Figs 8 , 16, 17 , 28 )

Type locality: Crawleys Creek , ca. 10 km W Nullica, SE New South Wales, Australia .

Type material: Holotype: Male : “nr. Crawleys Creek NSW 58.08093N 557 43253E J & R Miller 22.6.97”, “ Holotype Carabhydrus janmillerae sp. n. Hendrich & Watts des. 2008” [red printed label] ( SAMA) . Paratypes: 1 male with same data as holotype ( SAMA) ; 6 exs., “Headwaters Nullica riv NSW.58 93105N 557 48087E J&R Miller 24.6.97.” ( CLH, SAMA). All paratypes are provided with a red printed paratype label .

Description: Measurements: Holotype: TL = 2.5 mm, TL-H = 2.25 mm, MW = 1.15 mm. Paratypes: TL = 2.4–2.5 mm, TL-H = 2.15–2.25 mm, MW = 1.05–1.15 mm.

Color: Dorsal side testaceous brown to almost dark brown, ventral surface of head and thorax, and basal and apical margins of sterna 4–6, blackish ( Fig. 8 ). Antennae and palpi pale yellowish brown, without infuscation. Legs completely brown.

Sculpture: Head anterior to dorsal impression with deep punctures separated by a distance about one and a half their own diameter, and a very few sparse, minute 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 coarse punctures medially and laterally posteriad to eyes, remainder of space impunctate but with reticulate sculpture.

Pronotum with coarse and deep punctures separated by a distance about twice their own diameter; disc anterolaterally at base of front angle rugose with several coarse setiferous punctures; microreticulation absent. Elytron with punctation similar to that of pronotum but more dense, at least basally; interspaces smooth medially in male and with evident microreticulation in female; epipleuron with dense, more or less contiguous punctures.

Ventral surface with punctures similar in size than those of dorsal 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. Basal half of abdominal segments 2–4 strongly reticulated medially.

Structure: Head broad, with very small reduced 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; ventral surface lacking a crease behind eye; 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; most specimens with one to several additional shorter and more irregular rugae or impressions as well as 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; mesal groove beginning approximately opposite basolateral impression of pronotum, sharply defined on basal two-thirds, becoming shallower apically where on some specimens it is evident only as a series of more or less contiguous broad punctures which become obsolete shortly before apex; sublateral groove starting slightly mesad of humeral angle, slightly narrower and shallower than mesal groove, well defined on basal half to two-thirds, obsolete apically; epipleuron very gradually narrowed from shoulder to level of base of sternum 6.

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 broadened, antennomeres 5–7 slightly and progressively widened, 8–10 about as wide as long, and 11 fusiform. Profemur with anteroventral margin bearing four basal and a medial, short, stout spines. Protibia 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. Mesofemur clavate, ventral margin flattened and bearing a brush of elongate golden setae; inner margin of mesotibia without bearing an obtuse subapical tooth. Paramere sclerotized, broad, ovate, very much shorter than aedeagus; aedeagus ( Figs 15, 16 ) in ventral aspect slender, strongly bent and narrow medially and anteriorly, apex bilobed. Basal part of aedeagus with sclerotized, broad and shell-like coverage.

Female: Elytra with fine microreticulation. Females are a bit smaller than males. Measurements: TL = 2.4–2.45 mm, TL-H = 2.15–2.20 mm, MW = 1.05–1.10 mm.

Differential diagnosis: A very distinct species which can be easily separated from all other species in the genus by its very small eyes ( Fig. 8 ), the brown to testaceous surface and the very strange form of the median lobe ( Figs 16, 17 ).

Etymology: The species is dedicated to the ecologist Dr Jan Miller ( Australia) who collected the type specimens and recognized their distinctiveness.

Notes: A medium sized species showing some clear some stygobitic characters; body flattened, eyes very small. The punctures and microreticulation are not reduced and the colour, although relatively pale in some specimens, is similar to that of some other epigean Carabhydrus . In degree of adaptation to a subterranean life it appears to be similar to Limbodessus rivulus (Larson) which is found in the interstitial areas of small gravely streams in eastern Australia or even Paroster leai Watts & Leys, 2008 from SW Australia. Carabhydrus janmillerae sp.n. is the first species of the genus to show such intermediate characteristics.

Distribution: South-eastern corner of New South Wales. Only known from the two type localities west of Eden ( Fig. 28 ).

Habitat: A rheophilic species. A field trip by the senior author in the Nullica River area in November 2006 revealed no further specimens. After several years of reduced rainfall in the area the upper part of the Nullica River and its tributaries were completely dry.

Figures

FIGURES 5–9. Habitus of Carabhydrus. 5—Carabhydrus turaki sp.n. (holotype, female); 6—C. stephanieae (paratype); 7—C. mubboonus (female); 8—C. janmillerae sp.n. (paratype, female); 9—C. niger (female) (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.