Batrachomatus larsoni, Hendrich, Lars & Balke, Michael, 2013

Hendrich, Lars & Balke, Michael, 2013, Revision of Australian Matini diving beetles based on morphological and molecular data (Coleoptera, Dytiscidae, Matinae), with description of a new species, ZooKeys 293, pp. 41-64 : 47

Batrachomatus larsoni sp. n.

Allomatus new species: Larson 1993: 49 (cat.).

Type locality.

Creek, Windsor Tableland access road [16°13'55"S, 145°1'27"E], Queensland, Australia.

Type material.

Holotype ♂: "AUSTRALIA, QLD Windsor Tableland access rd km 40 Nov. 12/90 Larson" [white printed label], "Holotype Batrachomatus larsoni sp.n. Hendrich & Balke des. 2010" [red printed label] (ANIC). Paratype ♀ with same data as holotype (ANIC). The single paratype is provided with a red printed paratype label.

Description.

Measurements. Holotype: TL = 7.9 mm, TL-H = 7.1 mm; MW = 3.85 mm. Paratype: TL = 7.7 mm, TL-H = 7.0 mm; MW = 3.8 mm.

Colour. Dorsal surface shiny, black, appendages reddish.Head black with epistome and labrum lighter. Pronotum with reddish broad lateral margin. Elytron with narrow reddish band along 2/3 of length of elytron (Fig. 4).

Structure and sculpture. Body outline oblong oval, only slightly convex. Head, pronotal and elytral surface covered by polygonal double reticulation, smaller superficial meshes inside larger and more visible meshes, with punctures at intersections of all the larger meshes. Sides of pronotum moderately curved and convergent anteriorly. Sculpture on elytra as in pronotum but punctures at the intersections of all larger meshes smaller. Serial punctures on elytron distinct, large and shallow. On ventral side, metacoxal plate with very fine microreticulation, meshes very elongate, inside minutely and sparsely punctate. Lateral wings of metaventrite very narrow. Prosternal process flat, broad, broadly carinate in midline, parallel-sided, weakly pointed apically, weakly margined. Metacoxal lines well separated, strongly diverging anteriorly. Area between metacoxal lines with many small punctures.

Male. Pro- and mesotarsus a little dilated, basal 3 tarsomeres with dense short setae beneath suction cups. Aedeagus: median lobe (Fig. 9a, b); paramere (Fig. 9c).

Etymology.

This species is dedicated to our Canadian colleague David Larson (Maple Creek, Canada) who collected the only known specimens and recognized the species as new. The specific epithet is a substantive in the genitive case.

Affinities.

Batrachomatus larsoni sp. n. differs from Batrachomatus wilsoni by its smaller size ( Batrachomatus larsoni TL = 7.9 mmand Batrachomatus wilsoni TL = 8.4-8.5 mm), in the lack of any reddish humeral angles on elytra, the more flattened and narrowly formed body, and in having the reticulation on the elytra weak without punctuation, instead of moderately strong and punctate. Both species can be separated by the shape of their median lobes.

Distribution.

Only known from the type locality in NE Queensland (Fig. 14).

Habitat.

The Windsor Tableland is a granite plateau at about 1100 m, near to but further inland from Mt. Spurgeon and Mt. Lewis, in north-east Queensland. Because of its altitude, it receives enough rainfall to sustain mountain rainforest over much of the plateau surface, although it is surrounded by tropical eucalypt savannah at lower altitudes. Access to the Windsor Tableland is now for scientific study only, the public are permanently barred. A very detailed habitat description is given by Larson (1993): "Two specimens were collected from a low gradient section of a small, permanent, closed forest stream. The stream was largely shaded by a tall, more or less closed tree canopy. The stream bed was coarse sand and consisted of shallow, gentle riffles which separated pools formed where sand had been scoured from around and behind logs and from under tree roots to produce pools under overhanging roots-mats. The specimens were found swimming in a pool after the trailing roots on an overhanging bank on one side of the pool had been vigorously swept with a net. It is assumed the beetles came from under the bank but similar habitat, which was common along the stream, was searched without yielding additional specimens".