Carabhydrus monteithi Watts, 1978

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 : 13-14

Carabhydrus monteithi Watts, 1978

( Figs 18, 19 , 28 )

Carabhydrus monteithi Watts, 1978: 27 ; Zwick (1981: 170); Watts (1985: 23); Lawrence et al. (1987: 334); Larson & Storey (1994: 895, 900); Nilsson (2001: 144); Watts (2002: 32, 44).

Type locality: Boonoo Boonoo River , New South Wales, Australia .

Type material: Holotype: Male : “Boonoo Boonoo River via Legume N.S.W. 18.IV.1965 S.R.Curtis leg.”, “ Holotype Carabhydrus montheithi Det.C.Watts 1976” [white, hw label with red frame] ( QMB).

According to Watts (1978) a female paratype with same data as holotype is deposited in the collection of the Queensland University in Brisbane. This specimen was not studied .

Re-description: Measurements: Holotype: TL = 2.50 mm, TL-H = 2.30 mm, MW = 1.00 mm.

Color and sculpture as in C. mubboonus .

Structure: Head broad, 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; ventral surface lacking a crease behind eye; maxillary and labial palpi each with apical palpomere fusiform.

Pronotum narrow, sinuate basally and more or less straight and parallel before posterorlateral angles with lateral margins more or less parallel before right-angled hind angles; 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. Scutellum visible, 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, narrow, longitudinal groove each bearing a row of vague punctures, and a much less evidently defined lateral groove adjacent to lateral margin; mesal groove beginning approximately opposite basolateral impression of pronotum, very shallow but well defined on basal third, discontinuous before apex; sublateral groove starting slightly mesad of humeral angle, narrower and shallower than mesal groove, well defined on basal third obsolete apically.

Ventral surface and legs as in C. mubboonus .

Male: Antenna, femura and tibiae as in C. mubboonus . Parameres on holotype missing; aedeagus ( Figs 18, 19 ) in lateral aspect with a pair of medial spines on ventral margin.

Female: Not studied. According to Watts (1978) the female is a little broader and more parallel-sided.

Differential diagnosis: In size and shape C. monteithi is close to C. mubboonus but has a narrower appearance due to the pronotum being more strongly sinuate laterally with the lateral margins more or less parallel before the right-angled hind angles. Specimens of C. mubboonus have the elytral grooves deeper and broader and the mesal groove extending almost to the elytral apex whereas in C. monteithi it is very shallow in the apical third and discontinuous before the apex. In lateral aspect the aedeagus of C. monteithi ( Fig. 19 ) has a pair of medial spines on the ventral margin, which are lacking in C. mubboonus ( Fig. 20 ).

Distribution: Only known from two specimens from the type locality in northern New South Wales ( Fig. 28 ).

Habitat: Unknown. Most probably a rheophilic species. An intensive survey by the senior author and Gilbert Challet ( USA) in the Boonoo Boonoo National Park and adjacent areas in November 2001 and in October 2006 revealed no further specimens. After several years of drought and reduced rainfalls in the area the water quality of the Boonoo Boonoo river and its tributaries was very poor and most probably not a suitable habitat for Carabhydrus .

Figures

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 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.