Genus Dymasius Thomson

Dymasius Thomson, 1864, Syst. Ceramb., : 234 (type-species : Dymasius strigosus Th., 1864 = Cerambyx  macilentus Pasc., 1859) loc. cit. - Gahan, 1906b, Fauna British India, Col. 1 : 139. - Aurivillius, 1912, Coleopt. Cat., 39 : 60.

Elydnus Pascoe, 1869, Trans. Ent. Soc. Lond., ser 3, 3: 516 (type-species : E. amictus Pasc., 1869).

Microdymasius Picard, 1946, Misc. Ent., 42(9) : 110 (type-species : D. (M) angustatus Pic., 1925) loc. cit

Diagnostic characters : body elongated; head with a shallow or feebly groove between upper eye lobe; the latter very approximate; antennae very much longer than body in , sometimes 2 X as long, only slightly longer in ; antennal segment 3 & 4 nodose to subnodose; 6 - 10 angulated ectoapically in , less distinctive in ; prothorax distinctively longer than broad, at least 1.5 X longer, apical constriction narrower than basal; side of prothorax unarmed; intercoxal process of pro- and mesothorax vertical.

Note: this genus is divided into 2 subgenera as below. Hudepohl (1989) stated that this division is not justified and further argued that similar division by Gressitt & Rondon (1970) based on antennal length is not proper by the orginal description. However, in this study, Sarawak species showed remarkable differences on the third antennal segments relative to others.

Key to species of Dymasius in Sarawak

1.    Antennal segment 3 short, only slightly longer than 4, subequal or shorter than 1+2 united; apex of segment 3 & 4 strongly nodose (subgenus Elydnus .......................................................................................…… 2 
Antennal segment 3 very long, at least 2 X as long as 4 or distinctively longer than 1+2 united; segment 3 & 4 subnodose; prothorax transversely corrugate without longitudinal depression (subgenus Dymasius) - macilentus (PASCOE, 1859)

2(l) Elytra without sutural spine; frons with 2 crescentric fovaea facing each other side of middle; hind tibiae curved; antennal segment 4 & 5 with endoporiferous pits at base - amictus PASCOE, 1869
Elytra with sutural spine; frons with a A-shaped sulcus below antennal insertion; hind tibiae straight - sericatus PASCOE, 1869

Dymasius (Dymasius) macilentus PASCOE

Cerambyx macilentus Pascoe, 1859, Trans. Ent. Soc. Lond., ser 2, 5 : 20 (loc. cit.). 

Dymasius strigosus Thomson, 1864, Syst. Ceramb., 234 (loc. cit..) 

Dymasius macilentus : Gahan, 1906b, Fauna British India, Col. 1: 139.

Dymasius (Dymasius) macilentus: Aurivillius, 1912, Coleopt. Cat., 39: 60.

Head and prothorax black with pale tawny pubescence; antennae fuscous with fulvo-criscent pubescent; elytra fuscous tinged with castaneous at apex, pubescent arrangement on elytron giving an apperance of narrow longitudinal yellowish-grey stripes intervene with 3 - 4 subglabrous longitudinal brownish stripes; undersurfaces and legs entirely fuscous clothed with yellowish-grey pubescence.

Head exserted in front; frons oblique, with 2 deep foveae side of middle and a feebly raised diamond-shaped area; antennal insertion raised, lateral edge of antennifer extended to gena and somewhat convex; gula with an isolated transverse groove extended only to base of maxilla; an obscure groove between upper eye lobe; the latter approximate; neck granulose, very pubescent around ocular. Antenna 2 X as long as body in ; scape oblong, transverse, punctate and pubescent; 3 & 4 thicken at apex or subnodose; 3 very long, twice as long as 4 and distinctively longer than scape; 5 much longer than 4 but shorter than 3; 6 - 11 complanate, feebly angulate ectoapically in except terminal segment. Prothorax closely rugose except apical and basal constriction; the former narrower than the latter; corrugation on pronotum transverse, vermicular at sides; prosternum with a deep transverse groove in front and several transverse striate behind. Elytron 5 X as long as broad; apex obliquely truncated; angular spine much longer and stouter than sutural tooth; disc with longitudinal pubescent stripes alternating with sub-pubescent one, the former closely punctulate while the latter coarsely punctate; punctures at 1/5 from base coarser and sparsely separated. Legs : first hind tarsal segment as long as 2+3 united.

Measurement : Length 23 - 28 mm () ; breadth 5 - 6 mm ()

Distribution : Sarawak; Sri Lanka.

Material examined : 2 Kuching, Kuching Div., IV. 1905 (SM Coll.); Santubong, Kuching Div., V.1902 (SM Coll.).

Dymasius (Elydnus) amictus PASCOE

Elydnus amictus Pascoe, 1869, Trans. Ent. Soc. Lond., ser 3, 3 : 517. - Hudepohl, 1990a, Entomofauna, 11 (3/2) : 76.

Dymasius (Elydnus) amictus: Aurivillius, 1912, Coleopt. Cat., 39 : 60.

Head fuscous with dense hairy tawny pubescence; entire antennae fuscous, scape and apex of segment 3 - 5 castaneous, pubescence yellowish-grey; prothorax fascous, median with a glabrous longitudinal stripe flanked by another 2 tawny pubescent stripes at side; lateral-dorsal of pronotum bare; side of prothorax with dense tawny pubescence; elytra fusco-castaneous with glistering golden intermix with brownish mat oblong to irregular-shaped patches giving variable patterns; undersurfaces, femora and coxae fuscous with even and dense yellowish-grey pubescence; tibiae fusco-castaneous.

Head with frons, clypeus and antennifer neatly clothed with long hairy pubescence; external margin of frons roundly notched below antennal support with 2 crescentric foveae side of middle; antennal support only slight raised and deplanate from above. Antenna longer than body in both sexes, 2 X as long in , 1.5 X in ; scape subequal to segment 3; apex of 3 & 4 strongly nodose in , less so in ; endo-basal of segment 3 & 4 with poriferous pits in ; 5 subequal to 3, distinctively longer than 4; 6 - 10 subequal, 2 X as long as 3, angulate ectoapically in , less so in ; last segment 1.5 X as long as 10. Prothorax constricted at apex and base; the former narrower than the latter; longer than broad; a transverse groove behind apical constriction and 2 at base; pronotum intricate rugose at middle, side vermicular. Elytron 5 X as long as broad, gradually rounded near apex; subtransversely truncate with an angular cusp at apex but no sutural spine; disc silky pubescent; posterior portion overhanging at side of abdomen in both sexes. Legs : femora sublinear with apex widen; tibiae compressed laterally; hind tibiae curved.

Measurement : Length 24 mm (); 24 - 26 mm () 
Breadth 6 mm (); 6.5 - 7 mm ()

Distribution : Sarawak; Banda; Singapore; Philippines

Material examined : 1 Matang, Kuching Div., 26.VI.1911 (SM Coll.); 2 Kuching, Kuching Div., 16.VII.1900 (SM Coll.); Mt. Sibau, Balai Ringin Protected Forest, Samarahan Div., V.1902 (SM Coll.).

Dymasius (Elydnus) sericatus Pascoe

Elydnus sericatus Pascoe, 1869, Trans. Ent. Soc. Lond., ser 3, 3 :517.
Dymosius (Elydnus) sericatus : Aurivillius, 1912, Coleopt. Cat., 39: 60.

The coloration is similar to the previous species except that the prothorax is more pubescent.

Head short, triangular; frons with a A-shape sulcus below antennal insertion, lateral edge not notched; inner antennifer tuberculate posteriorly. Antenna robust; scape of asperate; nodose on segment 3 & 4 large, somewhat dilated internally; segment 3 fossulate endo-dorsally; 5 - 7 slightly expanded externally. Prothorax transversely and regularly rugose; a median raised area behind middle on pronotum; side of prothorax vertically but subparallelly corrugate. Elytron 4 X as long as broad; disc decline at 1/5 from apex; tip transversely truncate with a sutural spine, angular cusp abscure; overhanging over abdomen at posterior. Legs : femora fusiform; hind tibiae straight.

Measurement : Length 24 mm (); breadth 7 mm ()

Distribution : Sarawak; Banda

Note : another specimen identified as Dymasius pascoei, is most probably a of D. (E.) sericatus. It resembles in many characters except for (i) antennal segment 5 very short, only slightly longer than 4 while in the it is 2.5 X as long, (ii) lateral edge of frons strongly and roundly notched and (iii) antennal segment 3 & 4 not strongly nodose, segment 6 - 10 very much dilated and angulate ectoapically which agreed with Pascoe's remark (1869) on the of this species.

Material examined : 1 Kuching, Kuching Div., 17.VI. 1902 (SM Coll.)