Gerstaeckerus Tomaszewska, 2005

Tomaszewska, Wioletta, 2014, New species of the Amphisternus-group of Lycoperdininae from Philippines (Coleoptera: Endomychidae), Acta Entomologica Musei Nationalis Pragae 54 (2), pp. 635-644 : 641-642

Gerstaeckerus Tomaszewska, 2005

Engonius Gerstaecker, 1857: 220 (younger homonym of Engonius Perty, 1833 ). Type species. Engonius sexguttatus

Gerstaecker, 1857 subsequently designated by ARROW (1925): 310. Gerstaeckerus Tomaszewska, 2005: 42 (new substitute name for Engonius Gerstaecker, 1857 , redescription).

Diagnosis. Gerstaeckerus is most similar to Ohtaius and Brachytrycherus in general body appearance. However, the maxillary lacinia without tuft of S-like setae at apex and provided with short spinulae and two long spines on dorsal surface separate Gerstaeckerus from both genera. Moreover the body more elongate, the head lacking well developed, separated gular sutures, and the intercoxal process of mesoventrite widening apically and covering part of coxae, separate Gerstaeckerus from Brachytrycherus , while the femora without fringe of long hairs on inner surface can distinguish it from Ohtaius . Remarks. STROHECKER (1971) included 14 species in his review of the genus Engonius for which he also provided a key to their determination. He treated further four species as dubious taxa because of material unavailable for study. VAZIRANI & SAHA (1972) described a new species of Engonius from India, E. kamengensis . STROHECKER (1984) made some synonymies of Pic’s species including Engonius spurius Strohecker, 1971 (= E. trisignatus Pic, 1946 ). SHOCKLEY et al. (2009a) listed 20 species of Gerstaeckerus , although mistakenly treated G. similis humeralis (Arrow, 1928) once as species ( G. humeralis ) and thence as the subspecies. In fact the genus currently contains 19 species (with two subspecies of G. similis ). The updated key to the species of Gerstaeckerus provided below includes 15 species, leaving G. dalatensis (Pic, 1928) , G. luteofasciatus (Pic, 1940) , G. latenotatus (Pic, 1940) , G. herklotsii (Guérin-Méneville, 1857) as species incertae sedis, following STROHECKER (1971). The described new species here is the second species of Gerstaeckerus known from the Philippines. Key to the species of Gerstaeckerus (based on STROHECKER (1971))

1 Each elytron with one elongate orange-red fascia; Philippines (Mindanao). ................... ................................................................................................... G. rufiplagiatus sp. nov.

– Each elytron with two or three pale markings. ............................................................... 2

2 Elytron with two spots in anterior half. .......................................................................... 3

– Elytron with one spot, band or ring in anterior half. ...................................................... 7

3 Posterior elytral marking small, round. .......................................................................... 4

– Posterior elytral marking spanning most of elytral width. ............................................. 5

4 Pronotum shiny; body length 11.0–12.0 mm; Malaysia ( Sarawak, Perak, Penang), Indonesia (Sumatra). ........................................................ G. sexguttatus ( Gerstaecker, 1857)

– Pronotum subopaque; body length 9.0 mm; Malaysia (Borneo). ..................................... ............................................................................................... G. brookei (Gorham, 1885)

5 Elytral spots blood-red; Philippines. ..................... G. sanguineolentus (Gorham, 1875)

– Elytral spots orange or yellow. ....................................................................................... 6

6 Apex of prosternal process subtruncate; posterior elytral marking in form of large rectangle; Malaysia (Borneo), Singapore, Thailand. ............... G. trisignatus (Pic, 1946)

– Apex of prosternal process v-excised; posterior elytral marking in form of transversely oval bar; India. ........................................................... G. sikkimensis ( Strohecker, 1971)

7 Front elytral mark ring-like, enclosing umbo. ................................................................ 8

– Front elytral mark not ring-like. ................................................................................... 10

8 Pronotum granulate, opaque; body length 11.0– 12.5 mm; Malaysia, Indonesia (Sumatra, Java). ....................................................................... G. rubropictus ( Gerstaecker, 1857)

– Pronotum shiny, punctate; body length 9.0– 10.5 mm. ................................................... 9

9 Elytron with round pre-apical spot; body length 10.5 mm; Indonesia (Sumatra). ............ ......................................................................................... G. obliquus (Strohecker, 1957)

– Elytron with transverse posterior marking; body length 9.0 mm; Java, New Guinea. ..... ................................................................................ G. perspicillaris ( Gerstaecker, 1857)

10 Elytron with dentate cross-band in front. ..................................................................... 11

– Elytron with round, oval or dumbbell marking in front. .............................................. 13

11 Elytral cross-bands strongly dentate. ........................................................................... 12

– Elytral cross-bands weakly dentate; Vietnam. ........ G. similis humeralis (Arrow, 1928)

12 Deeply black, feebly shiny; body length 9.0–10.0 mm; Cambodia, China, India, Laos, Myanmar, Thailand, Vietnam. ................................................ G. gratus (Gorham, 1891)

– Black, shiny; body length 7.5 mm; China. .......... G. chensicieni (Kryzhanovskij, 1960)

13 Front elytral markings deeply constricted; Singapore, Malaysia (Perak). ........................ ....................................................................................................... G. junctus (Pic, 1930)

– Front elytral markings round or oval. ........................................................................... 14

14 Elytra widest beyond mid length; elytral markings round; body length 7.0– 7.6 mm; India. .................................................................. G. kamengensis ( Vazirani & Saha, 1972)

– Elytra widest at mid length; elytral markings transversely or obliquely oval. ............. 15

15 Body short-oval, elytra highest basad; length 8.0–9.0 mm; Malaysia, Myanmar, Singapore, Sumatra, Thailand. ........................................................ G. gibbosus (Gorham, 1885)

– Body long-oval, elytra highest near middle. ................................................................ 16

16 Elytral outline arcuate; body more oval; 10.0 mm; Malaysia, Myanmar, Sumatra, Thailand. .................................................................................... G. klugi ( Gerstaecker, 1857)

– Elytral outline subparallel; body more elongate; length 10.0–11.0 mm; Laos, Thailand, Vietnam. ........................................................................ G. similis similis (Arrow, 1920)