Gymnanthelius porchi, Perkins, Philip D., 2004

Perkins, Philip D., 2004, A revision of the Australian endemic water beetle genus Gymnanthelius Perkins (Coleoptera: Hydraenidae), Zootaxa 585, pp. 1-39 : 13-16

Gymnanthelius porchi new species

( Figures 1 , 5 , 15 , 21 )

Type Material. Holotype (male): Australia, Victoria, Possum Hollow falls, W. br. Tarwin River, 5.6 km SSW. Allambee, ex sandy mud between cobbles at edge of riffle 0.1 km below waterfall; wet sclerophyll forest (Eucalyptus regnans), elev. 240 m, 38° 19' S, 146° 1' E, 14 January 1999, N. Porch (NP 18); deposited in the ANIC. Paratypes (234): Same data as holotype (63 ANIC, NPC). Victoria, 1 km N. Possum Hollow, W. br. Tarwin River, 4.6 km SSW. Allambee, ex shaded silty mud at edge of small 'creek' at pasture­wet sclerophyll forest boundary, elev. 240 m, 38° 18' S, 146° 1' E, 14 January 1999, N. Porch (NP 19) — (13 ANIC); Allambee, 6.2 km SSW. of, falls on the West Branch of Tarwin River, seeps and splash­zone of steep rocky cascading 'falls' in wet sclerophyll forest beside road, elev. 220 m, 38° 19' S, 146° 1' E, 9 April 2000, N. Porch (NP 73) — (2 ANIC); Big Tree Creek, at Tanjil River, East Branch, 4km SE. of Tanjil Bren, littery sand at edge of small roadside section of creek; wet sclerophyll forests surrounds, elev. 495 m, 37° 49' S, 146° 11' E, 10 December 2000, N. Porch & R. Porch (NP 7) — (7 ANIC); Elizabeth Ck., 1.2 km S. Childers, very abundant in sandy mud and wet litter (80cm by 20cm) along edge of small forest creek in wet sclerophyll forest (Eucalyptus regnans), elev. 195 m, 38° 19' S, 146° 6' E, 28 October 1998, N.Porch (NP 9) — (68 ANIC); Franklin River at South Gippsland Highway, on and in shaded silty mud at edge of small 'creek' in pasture, elev. 10 m, 38° 39' S, 146° 18' E, 13 January 1999, N. Porch (NP 14) — (9 ANIC); Gembrook, south of;, muddy litter of small mud/sand banks of small, shaded, forest stream; wet sclerophyll forest, elev. 245 m, 37° 55' S, 145° 32' E, 8 April 2000, N. Porch & N. Krause (NP 63) — (17 ANIC); Healesville, Dandenong Ranges, 37° 39' S, 145° 32' E, 1–30 December 1968, C. Watts — (1 SAMA); Latrobe River at Piedmont, gravel at edge of river at pasture/forest boundary, elev. 255 m, 37° 53' S, 145° 54' E, 1 January 2003, N. Porch & N. Krause (NP 54) — (5 ANIC); Little Morwell River, 3.8 km NNE. Mirboo North, sandy mud and litter accummulation at edge of small creek; dry/moist riaprian sclerophyll forest, elev. 165 m, 38° 22' S, 146° 10' E, 3 October 1999, N. Porch (NP 45) — (7 ANIC); same locality, elev. 165 m, 38° 22' S, 146° 10' E, 24 February 2001, N. Porch & Latrobe Valley Field Naturalists ( LVFN) (NP 10) — (5 ANIC); Little Morwell River at Mirboo Nth — Morwell Rd., 3.75 km NNE Mirboo North, on and in shaded muddy sand at edge of 'small creek' in dry sclerophyll forest, elev. 165 m, 38° 22' S, 146° 11' E, 14 October 1998, N.Porch (NP 8) — (6 ANIC); Little Morwell River, at Ricardo Road, Darlimurla, litter and mud at edge of small creek in dry sclerophyll forest, elev. 250 m, 38° 22' S, 146° 12' E, 9 April 2000, N. Porch (NP 49) — (7 ANIC); Morwell River, 6.1 km SSE. Boolarra on Morwell River Road (Apex Park), willow roots and sandy mud/gravelly mud at edge of small river; under weeping willows, elev. 115 m, 38° 25' S, 146° 18' E, 29 November 1999, N. Porch (NP 38) — (3 ANIC); Morwell River, u/s of falls on, SE. of Olsens Bridge, gravel at edge of small creek in regrowth wet sclerophyll forest, elev. 225 m, 38° 30' S, 146° 20' E, 9 April 2000, N. Porch & N. Krause (NP68) — (17 ANIC); Traralgon Ck., 0.2 km N. 'Hogg Bridge', 5.0 km NNW. Balook, silty sand on small sandbank in creek (low water) backwater in wet sclerophyll forest, elev. 170 m, 38° 24' S, 146° 32' E, 13 January 1999, N. Porch (NP10) — (4 ANIC). Representative specimens deposited in AMSA, BMNH, CMNH, FMNH, MCZ, MVMA, QMBA, QPIM, SAMA, TMSA, UQIC, USNM, and WA M P.

Diagnosis. A very distinctive species, recognized by the black shining dorsum with faint metallic reflections, the deeply striate­impressed elytral series, the comparatively wide elytral intervals, the distinctive subdeltoid pronotal shape ( Fig. 1 ), and the entirely hydrofuge pubescent metasternum.

Description. Holotype 1.86 x 0.86; head length 0.37, width 0.48; pronotum midlength 0.44, maximum width 0.59 just behind anterior angles; elytra length 1.11, maximum width 0.86. Form moderately ovate, transversely quite convex. Dorsum black, legs dark brown, elytra strongly shining, pronotum shining but less so.

Clypeus disc strongly shining and with a few punctures as large as those on pronotum, lateral areas effacedly mcr., dull, sparsely pubescent; interocular foveae deep, large, each nearly as wide as distance separating them, margins gradual, bottom with vaguely 8­ shaped pit; ocelli distinct, transverse. Frontoclypeal suture deeply impressed, arcuate. Clypeus length:width as 7:14, anterior angles each minute acuminate point, effacedly mcr. and dull laterally, shining on disc and along anterior margin; coarsely moderately densely punctate basally, becoming finer apically. Labroclypeal suture nearly straight in dorsal view, evenly arcuate in anterior view. Labrum length:width as 4:14; anteriorly produced in two lobes separated by U­shaped median emargination with very slightly reflexed margin; each lobe about 2x length of last maxillary palpomere, setae short but distinct on disc, laterally forming short fringe. Maxillary palpomere 3 about 3x length of 4.

Pronotum anterior margin almost evenly arcuate from side to side, only very weakly produced in front of lateral depressions; anterior hyaline border well developed; each lateral depression four times as wide anteriorly as posteriorly, side weakly emarginate before tooth­like posterior angle. Lateral hyaline border well developed, anterior extreme nearly attaining anterior angles, widest just anterior to tooth­like posterior angle of lateral depression, in dorsal aspect margin oblique to midline, weakly arcuate except slightly indented opposite posterior extreme of lateral depression. Lateral fossulae deep, sinuate, inner margin abrupt, outer margin obsolete; without anterior or posterior pit. Disc transversely convex, narrowing slightly over anterior 0.2, then widening to slightly beyond midlength, then sides converging slightly to base; moderately shining, very effacedly mcr., reliefs moderately densely and coarsely to moderately finely punctate. Median groove moderately wide, widest near anteerior extreme, then gradually tapering to posterior, each end tapering and not attaining respective hyaline border. Anterior foveae absent or only very faintly indicated by shallow transverse impression. Posterior foveae absent.

Elytra shining, widest slightly before middle, sides more strongly arcuate in front of than behind middle, disc transversely quite convex, posterior declivity rather abrupt, summit at midlength. Disc with five rows of small punctures in deep striae between suture and prominent humeral umbo, each puncture with minute recumbent seta; series 2 and 3 terminating beyond summit of posterior declivity, 1 and 4 attaining apices. Intervals transversely rounded, 3– 4 x puncture width. Explanate margin well developed, widest before midlength, nearly as wide as metatibia, declivous, surface flat or only slightly transversely convex, origin just behind anterolateral angles, becoming obsolete near posterior 0.2, with vert short sparse indistinct recumbent setae. Apices in male conjointly rounded.

Metasternum entirely hydrofuge pubescent. Ventrites 1–4 with hydrofuge pubescence.

Aedeagus: Length 0.35 mm.; mainpiece slightly sinuate, apex slightly asymmetrical, wedge­shaped; distal part of internal tube oval in ventral aspect; parameres with distal pair of setae relatively short ( Fig. 15 ).

Etymology. Named in honor of the collector, Nicholas Porch.

Distribution. Currently known from southern Victoria ( Fig. 21 ).

Figures

FIGURE 1. Gymnanthelius porchi holotype. Dorsal structures and sculpture.

FIGURE 5. Gymnanthelius porchi holotype. Dorsal and lateral habitus.

FIGURES 14 – 17. Gymnanthelius aedeagi. — 14. G. hieroglyphicus (specimen from NSW, Khancoban). — 15. G. po rc h i (holotype). — 16. G. tu nic u s (holotype). — 17. G. maxipunctus (holotype).

FIGURES 18 – 21. Gymnanthelius geographical distributions. — 18. G. clypeatus. — 19. G. cupreus. — 20. G. lamingtonensis. — 21. G. porchi.