Akamboja, Roza & Quintino & Mermudes & Silveira, 2017

Roza, André Silva, Quintino, Hingrid Yara Souza, Mermudes, José Ricardo Miras & Silveira, Luiz Felipe Lima Da, 2017, Akamboja gen. nov., a new genus of railroad-worm beetle endemic to the Atlantic Rainforest, with five new species (Coleoptera: Phengodidae, Mastinocerinae), Zootaxa 4306 (4), pp. 501-523 : 503-504

Akamboja gen. nov. Roza, Quintino, Mermudes & Silveira

Type species. Akamboja minimum Roza, Quintino, Mermudes & Silveira sp. nov., by original designation.

Etymology. The following radicals come from the Guarani language: Akã = branch, and Mboja = fused, glued ( Dooley 1998). The name denotes the fused branches of ninth antennomere. Gender neutrum.

Diagnosis. Body overall small, around 4 mm ( Figs 1 and 2 ); antenna with ten antennomeres, IV to VIII with two short symmetrical branches, 1.5 to 2x the size of the antennomere; branches of antennomere IX fused in a singular flabellum, slightly depressed medially ( Figs 3 and 10 ); mandible small, curved downwards ( Figs 7 and 8 ); posterior tentorial pit consisting of a single small fossa ( Figs 11 and 12 ); pronotum narrower than humeral distance ( Fig. 1 ); elytron short, surpassing the second to fourth abdominal segment (depending on species), 3– 4x longer than wide, slightly convergent posteriorly, thickened apically, sometimes with a white or pale yellow spot ( Fig. 15 ); first tarsomere of anterior leg with a ventral comb as long as the tarsomere ( Figs 17 and 18 ); claws with six long and asymmetrical teeth ( Figs 19 and 20 ); aedeagus with patch of bristles at paramere apex ( Figs 21 and 22 ).

Description, male.

Coloration: Body overall light brown to dark yellow. Pronotum dark to light brown. Elytron almost black to light brown, apex pale yellow, sometimes light brown. Wing venation black to light brown.

Head ( Figs 6 and 7 ). Head wider than long or as wide as long, fully exposed, prognathous; slightly wider than pronotum; integument glossy, coarsely punctured; antenna shorter than elytron; 10-segmented, antennomere short, IV and IX slightly smaller than V-VIII, X flattened and rounded, IV-VIII with two short, symmetrical branches, IX with branches fused in a singular flabellum, slightly depressed medially ( Figs 3 and 10 ); eyes finely faceted, almost spherical, as long as 1/2 to 1/3 head length in lateral view, frons plan, wider than antennomere I length, clypeus fused to frons, both coarsely punctured; labrum small and free, apically notched ( Figs 7 and 8 ), 5x wider than long; mandibles very thin, 3x longer than wide, curved down; Maxillary palpi 4-segmented, IV securiform, 3– 4x longer than the third, coarsely punctured on anterior half, finely punctured on posterior half ( Fig. 9 ); labial palpi 2- segmented, small and thin, covered by mandibles, last segment rounded; tentorial pit consisting of a single fossa ( Figs 6 , 11 and 12 ), apodeme indistinct; gular sutures contiguous.

Thorax ( Figs 5–6 , 13 and 15 ). Pronotum quadrangular, as long as wide, anterior angles dorsally concave, lateral margins divergent posteriad, posterior angles medially notched, integument glossy, finely punctured ( Fig. 5 ); Mesesternum, mesepimeron and mesepisternum with lateral setae and obliterated sutures ( Figs 13 and 14 ). Elytron short, surpassing the second or third abdominal segment, 3– 4x longer than wide, wider in anterior half, subparallel, apex swollen, moderately setigerous punctured ( Fig. 15 ); posterior wings with radial cell closed, reduced, and variable in size (sometimes in the same individual), vein r4 interrupted ( Fig. 16 ); legs increasing in length, protarsomere I with ventral comb as long as the tarsomere ( Figs 17 and 18 ), 1/2 the length of meso and metatarsomere I, tarsomere IV of all legs 1/ 2 V length, claws pectinate, with six long and asymmetrical teeth ( Figs 19 and 20 ).

Abdomen ( Fig. 2 , 21–22 ). Densely punctate and setose; aedeagus ( Figs 21 and 22 ) trilobed, median lobe cylindrical, strongly curved at base, acuminate apically, with many tiny glandular openings; flagellum encircled around median lobe at rest; about as long as median lobe length; base of flagellum with two protuberances ( Fig. 22 ); parameres parallels, elongate, oval, narrowed to apex, setose and bidentate at the inner side.

Length. 3.3 to 4.8 mm.

Female and immature stages. Unknown.

Biology and distribution. Akamboja gen. nov. only occurs on mountain areas, with at least 150m of altitude. It is usually caught during spring and summer, which in Brazil begins at end of September and lasts to the end of March. Only one specimen of Akamboja monteirorum sp. nov. was caught outside this margin, in May, that corresponds to autumn in the southern hemisphere. Species of this genus were never seen alive, so there is no data regarding their habits. It occurs in montane and ombrophilous forests, along several localities of the Serra do Mar and the Serra da Mantiqueira mountain ranges.

Remarks. Zaragoza-Caballero’s key (2010) to Mastinocerinae genera would place Akamboja in Decamastinocerus Wittmer, 1988 from Venezuela, as it has antenna with ten antennomeres. Although Akamboja gen. nov. is morphologically similar to Decamastinocerus , it can be easily distinguished by the larger size (from 3.3 to 4.8 mm in Akamboja , 2.5 mm in Decamastinocerus ), interantennal space almost twice scape length (smaller in Decamastinocerus ), fused branches of the ninth segment (separated in Decamastinocerus ), larger eyes (occupying less than half of head in Decamastinocerus ), head wider than the pronotum (as wide as pronotum in Decamastinocerus ), and elytron completely setose (apically setose in Decamastinocerus ); claws with six long and asymmetrical teeth (with three small medial teeth in Decamastinocerus ).

This new genus is very homogeneous morphologically. However, species have remarkable intraspecific variation, especially in color patterns, eyes, palpomeres, wing and elytra size. The radial cell, for example, can be very small in a wing and large in the other wing of the same individual. As for the colour pattern, the older specimens, which are exposed to ethanol for longer periods, show more pale and homogeneous coloration. Therefore, the color variation could be an artifact of the method of conservation.

Figures

FIGURES 1 – 6. Akamboja minimum sp. nov. 1 habitus, dorsal. 2 habitus, lateral. 3 antenna, lateral. 4 head and pronotum, lateral. 5 head and pronotum, dorsal. 6 head, ventral.

FIGURES 9 – 10. Akamboja minimum sp. nov., Scanning electron micrographs. 9 maxillary palpi, last palpomere. 10 antenna, two last segments.

FIGURES 7 – 8. Akamboja minimum sp. nov., Scanning electron micrographs. 7 head, frontal. 8 clypeus and mandibles, frontal.

FIGURES 11 – 12. Akamboja minimum sp. nov., Scanning electron micrographs. 11 head, ventral. 12 tentorial pit, close.

FIGURES 13 – 16. Akamboja minimum sp. nov. 13 meso and metathorax, lateral. 14 meso and metathorax, ventral. 15 elytron, dorsal. 16 hind wing, dorsal.

FIGURES 17 – 18. Akamboja minimum sp. nov., Scanning electron micrographs. 17 protarsus, first tarsomere, comb, ventral. 18 protarsus, first tarsomere, comb, ventral, close.

FIGURES 19 – 20. Akamboja minimum sp. nov., Scanning electron micrographs. 19 protarsus, claw, ventral. 20 tooth of claw, close.

FIGURES 21 – 22. Akamboja minimum sp. nov., Scanning electron micrographs. 21 aedeagus, frontal. 22 aedeagus, tip, dorsolateral.