Phaenostoma kontax, Gustafson & Short & Aezs, 2010

Gustafson, Grey T. & Short, Andrew E. Z., 2010, Redescription of the Neotropical water scavenger beetle genus Phaenostoma (Coleoptera: Hydrophilidae) with description of two new species, Acta Entomologica Musei Nationalis Pragae (suppl.) 50 (2), pp. 459-469 : 464-465

Phaenostoma kontax sp. nov.

( Figs. 2A , 3 , 4B )

Type locality. Peru, Loreto Department, Campamento San Jacinto, 2º18.75 ′ S, 75º51.77 ′ W.

Type material. HOLOTYPE: ♁, ‘PERU: Dept. Loreto / Campamento San Jacinto / 2º18.75’S, 75º51.77’W / 6 July 1993, 175– 215 m / Richard Leschen #39 / ex. Rainforest berlese’ , ‘ HOLOTYPE / Phaenostoma / kontax sp. nov. / des. Gustafson & Short’ ( KSEM) . PARATYPES (21 exs.). PERU: LORETO DEPARTMENT: same data as holotype (10 exs., KSEM, NMPC, NHMW) ; same locality but 11.vii.1993, leg. Richard Leschen #86, ex. flower fall berlese (4 exs., KSEM) ; same locality but 10.vii.1993, leg. Richard Leschen #80, ex flower fall berlese (4 exs., KSEM) ; same locality but 2.vii.1993, leg. Richard Leschen #1, ex Berlese,Qd. 22 (2 exs., KSEM) ; 1.5 km Teniente Lopez , 2º35.66’S 76º06.92’W, 210–240 m, 21.vii.1993, leg. Richard Leschen #169, ex. rainforest berlese (1 ex., KSEM) .

Diagnosis. Body size 2.1–2.3 mm. Body form weakly convex. Elytral margins explanate. Sternal process constricted at junction of meso- and metaventrites, form as in Fig 2A . Aedeagus as in Fig. 4B with very thin and strongly inwardly curved parameres.

Phaenostoma kontax sp. nov. is easily distinguished from other known Phaenostoma by its small size (it is the smallest known species of Phaenostoma ), weak body convexity, and elytra with explanate margins apically. Phaenostoma stochasma sp. nov. is similar in body form and relatively smaller size but can be easily distinguished by the shape of its aedeagus ( Fig. 4B ) and sternal process. Phaenostoma kontax sp. nov. has the anterior hood of the sternal process appearing above the rest of the plane of the rest sternal process, while that of P. stochasma sp. nov. is located on the same plane as the rest of the sternal process.

Description. Color. Dorsal surface appearing reddish brown to brown. Elytral and pronotal discs frequently darker, with the lateral margins often appearing paler in color. Head with darker coloration frequently around the eyes with the clypeus lighter brown to reddish brown anteriorly. Ventral surface reddish brown to brown with legs lighter brown to near yellow. Tarsi, palps, and antennae yellow.

Head. Ground punctation fine with average distance between punctures ca. 3–4× the distance of one puncture.

Thorax. Pronotum punctation fine with the average distance between punctures ca. 4–5× the diameter of one puncture. Elytral punctation coarse (but weakly impressed), with the average distance between punctures ca. 2–3× the diameter of one puncture ( Fig. 3A ); most punctures set within a larger recessed disc ( Fig. 3B ). Elytral margins apically explanate. Process of the mesoventrite broad and constricted at suture with metaventrite ( Fig. 2A ), with anterior hood thickly bordered and frequently appearing above the rest of the plane of the sternal process in lateral view.

Abdomen. Aedeagus ( Fig. 4B ) with parameres thin and strongly curved inward, with the bases fairly thick. Phallobase weakly constricted. Apex of median lobe not reaching the apex of the parameres.

Etymology. Kontax is a Greek expression for a spear, referring to the spear-shaped anterior portion of the sternal process. Treated as noun in apposition.

Distribution. Known only from a few localities in Amazonian Peru.

Remarks. All specimens of this species were taken from rainforest berlese samples, including ‘flower falls’, suggesting this species may be a terrestrial/leaf-litter and/or decaying vegetation inhabitant.

Figures

Fig. 2. Sternal process of Phaenostoma species. A – P. kontax sp. nov.; B – P. posticatum (Sharp, 1887); C – P. stochasma sp. nov.

Fig. 3. Elytron of Phaenostoma kontax sp. nov. A – entire elytron; B – enlargement of elytral surface.

Fig. 4. Aedeagi of Phaenostoma species. A – P. posticatum (Sharp, 1887) (Costa Rica); B – P. kontax sp. nov. (holotype); C – P. stochasma sp. nov. (holotype; Costa Rica); D – P. stochasma sp. nov. (paratype; Venezuela). Scale bar = 0.2 mm.