Arcastes Baly 1865
Creators: name: Hazmi, Izfa Riza
name: Wagner, Tomas
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Arcastes

description: Redescription <i>Arcastes</i> Baly, 1865 Type species. <i>Arcastes biplagiata</i> Baly, 1865 by original designation. <b>Total length.</b> 4.45–7.35 mm (mean: 5.67) <b>Head.</b> Brownish-red to red. Very finely punctuated, with significant transverse impression between posterior third of eyes. Eyes large, strongly convex (Fig. 1). Labial palpi slender and maxillary palpi enlarged, occasionally dark brown to black (Fig. 2a). Labrum pale to dark brown and occasionally blackish in middle. Mandible pale yellow to dark brown and blackish towards apex. Antennae elongated, extended to apical third of elytra (Fig. 1); third to terminal antennomere densely covered by bristle-like setae. First to eighth or ninth antennomeres black, two to three terminal antennomeres contrasting pale yellow to yellowish-brown, only in <i>A. dimidiata</i> two basal antennomeres also yellowish. First antennomere club-shaped, second shortest, third antenno- <b>Table |.</b> Numbers of material examined and collections investigated. <b>Figure |.</b> <i>Arcastes biplagiata</i> Baly, 1865. Dorsal colour pattern. scale bar: 1 mm (same for all following Figures) mere about two times longer than second; ratio length of second to third antennomere 0.50–0.57 (mean: 0.54); third to seventh antennomere broad, significantly enlarged, ratio length of third to fourth antennomeres 0.60–0.70 (mean: 0.65), eighth to eleventh antennomeres much slenderer (Figs 8, 14, 20). <b>Thorax.</b> Pronotum transverse, very broad, broadest in middle, anterior angle significantly protruding, posterior angle slightly marked, pronotum with deeply impressed line along lateral margins (Fig. 1). Brownish-red to red as head, shiny, smooth, and finely punctuated, without transverse depression. Pronotal width 1.55–2.25 mm (mean: 1.90), ratio length to width 0.48–0.57 (mean: 0.53). Scutellum large, triangular, impunctate, brownish, red or black. Procoxal cavities partly open (Fig. 2b). Meso- and metathorax reddish-brown to black. Metasternum broad (Fig. 2c). Elytra elongated, either black throughout, or black with longitudinal yellowish-red spot on disc of each elytron, or black with yellowish to reddish suture that in some species reaches <b>b</b> up to one third of each elytron, or basal third completely red and apical two thirds black. Elytra shiny, punctation fine, irregular, slightly coarser and denser than that of pronotum. Elytral length 3.80–5.90 mm (mean: 4.73), maximum width of both elytra together 1.50–4.00 mm (mean: 2.79), ratio of maximum width of both elytra together to length of elytra 0.61–0.72 (mean: 0.66). Alae fully developed (Fig. 4). Legs long and slender, basi-metatarsus elongated (Fig. 5), coxa and trochanter reddish like underside, femur, tibia and tarsus black throughout, tibia with dense and fine setae. <b>a</b> <b>b</b> <b>c</b> <b>Abdomen.</b> Pale yellow to reddish-brown, occasionally darker in middle, and seventh sternite usually dark brown to black. Last visible sternite in females rounded at apex, and in males with two deep, parallel-sided incisions (Fig. 3). <b>Male genitalia.</b> The outer shape of median lobe is symmetrical, strongly sclerotized, apex tapered, slightly rounded and not incised. Orifice wide, more or less circular to slightly rectangular. Endophallic structures asymmetrically arranged, ventral spiculae hammer-like, median spiculae narrower, slender, lateral spiculae enlarged and slender, with claw-like small spine medially and tube-like, curved spines. Tectum not incised at apex, almost reaching apex of the median lobe, constricted at middle part and enlarged at base (Figs 9, 15, 21). <i>A. dimidiata</i> <i>A. biplagiata</i> I 2–3 4–6 7–I3 <b>Female genitalia.</b> Spermatheca with oval to slender and elongated nodulus. Middle part long and slightly curved, cornu long and curved (Figs 10, 16, 22). Without stronger sclerotized bursa sclerites. <b>Distribution.</b> The species are restricted to South-East Asia and up to now only recorded from Singapore, Malaysia (Peninsular) and Indonesia (Borneo, Sumatra), southwards to Java (Figs 6, 17). <b>Diagnosis.</b> Beetles of the genus <i>Arcastes</i> are medium sized Galerucinae with strongly elongated basi-metatarsus, without pronotal impressions, reddish head and pronotum and usually contrasting black antennae, legs and elytra, the latter often with yellowish to red spots, suture or base. The significantly enlarged third to eighth antennomeres are very characteristic. <i>Arcastes</i> is the most similar to <i>Neolepta</i> Jacoby, 1884, with the type species, <i>Neolepta biplagiata</i> Jacoby, 1884, looking very similar to <i>Arcastes biplagiata</i> at the first glance. Antennae of these beetles are similar with slightly to strongly enlarged antennomeres in the middle, while terminal antennomeres in <i>Neolepta</i> are also black, the basal two antennomeres are reddish, and much slenderer than in <i>Arcastes</i>. The dorsal coloration is also similar, but <i>N. biplagiata</i> posses a pale yellowish transverse band or nearly circular spot in the middle of each elytron. The genitalic patterns of both sexes possess very strong differences. Asymmetric endophallic spiculae of certain shape (Figs 9, 15, 21) as in <i>Arcastes</i> are a unique pattern in oriental galerucines with elongated basi-metatarsus, while the median lobe in <i>Neolepta</i>, as in <i>Monolepta</i>, and <i>Candezea</i>, is narrower and has symmetrically arranged endophallic spiculae which are much smaller (cf. Wagner 2001, Wagner and Kurtscheid 2005). The shape of spermatheca of <i>Arcastes</i> resembles that of <i>Monolepta</i>, but in <i>Arcastes</i> it lacks sclerotized bursa-sclerites, while in <i>Monolepta</i> there are two distinct types of this structure. Also <i>Neolepta</i> and <i>Candeza</i> have strongly sclerotized bursa-sclerites. The pronotum of <i>Arcastes</i> (ratio length to width 0.48–0.57), is on average broader than in <i>Monolepta</i> and <i>Neolepta</i> (0.52–0.65), and within the range of <i>Candezea</i> (0.42– 0.59). Procoxal cavities are similarly structured (partly open) in all these genera. The third antennomere of <i>Arcastes</i> is roughly twice as long as the second (ratio length of second to third antennomere: 0.50–0.57), which is similar to <i>Candezea</i> (0.49–0.63) but different from <i>Neolepta</i> and <i>Monolepta</i> which both have the second and third antennomere of about equal length (0.82–1.10). While <i>Candezea</i> have strongly elongated, slender antennomeres, <i>Arcastes</i> species can be clearly differentiated by the enlarged median ones. <b>Redescriptions of species</b>
description: Published as part of <i>Hazmi, Izfa Riza &amp; Wagner, Tomas, 2010, Revision of Arcastes Baly, 1865 from the Oriental Region (Coleoptera, Chrysomelidae, Galerucinae), pp. 79-99 in ZooKeys 42 (42)</i> on pages 81-86, DOI: 10.3897/zookeys.42.336, http://zenodo.org/record/576653
description: {"references": ["Baly JS (1865) Description of new genera and species of Gallerucidae. The Entomologists Monthly Magazine 2: 147 - 148.", "Jacoby M (1884) Description of new genera and species of phytophagous Coleoptera collected by Dr. B. Hagen at Serdang (East Sumatra). Notes from the Leyden Museum 6: 201 - 230.", "Laboissiere V (1929) Spolia Mentawiensia - Phytophaga - Galerucini nouveaux ou peu connus. Bulletin of the Raffles Museum 2: 91 - 96.", "Wagner Th (2001) Revision of Afrotropical Monolepta Chevrolat, 1837 (Coleoptera: Chrysomelidae, Galerucinae). Part II: Species with red elytra, pronotum and elytra, with descriptions of new species. Bonner Zoologische Beitrage 50: 49 - 65.", "Wagner Th, Kurtscheid A (2005) Revision of Candezea Chapuis, 1879 (Coleoptera: Chrysomelidae: Galerucinae) from continental Africa. Journal of Natural History 39: 2591 - 2641."]}