Amasa cylindrotomica (Schedl, 1939)

Sittichaya, Wisut, Smith, Sarah M. & Beaver, Roger A., 2019, Ten newly recorded species of xyleborine ambrosia beetles (Coleoptera, Curculionidae, Scolytinae, Xyleborini) from Thailand, ZooKeys 862, pp. 109-127 : 112-113

Amasa cylindrotomica (Schedl, 1939) Fig. 3 A–E

Pseudoxyleborus cylindrotomicus Schedl, 1939: 40.

Xyleborus cylindrotomicus (Schedl): Schedl 1942: 6.

Xylosandrus cylindrotomicus (Schedl): Wood 1989: 177.

Amasa cylindrotomica (Schedl): Dole and Cognato 2010: 525.

Synonyms: Xyleborus semitruncatus Schedl, 1942: 35. Synonymy: Schedl 1951: 79; Wood 1989: 177.

Xyleborus truncatellus Schedl, 1951: 79. Synonymy: Kalshoven 1959: 95.

Xyleborus jucundus Schedl, 1954: 138 (new name for Xyleborus truncatellus Schedl, 1951 non Schedl 1949). Synonymy: Kalshoven 1959: 95.

Diagnosis.

Small, 2.1 mm (N = 1) long; stout, 2.0 times longer than wide; body shining, nearly glabrous, yellowish brown to brown in color; eye deeply emarginate; antennal club with sutures obscured (type 5; Hulcr et al. 2007); pronotum from dorsal view round (type 1; Hulcr et al. 2007) front broadly convex, from lateral view round near (type 1; Hulcr et al. 2007), anterior half of pronotum densely, finely asperate, base very finely punctate; elytra 1.07 times as long as pronotum, sides subparallel, widest at declivital summit, declivity dull, glabrous, strial punctures seriate, first stria straight, second and third laterally diverging, interstriae shagreened, two times broader than striae.

Material examined.

THAILAND, Ton Nga Chang Wildlife Sanctuary, Songkhla Province, 6°59'32.1"N 100°08'57.8"E, tropical rainforest, ethanol-baited trap, 01.ii.2014 (1) (W. Sittichaya).

Distribution.

Indonesia (Java, Sumatra). New to Thailand.

Biology.

Recorded only from Syzygium aromaticum Merr & LM Perry (clove) ( Myrtaceae ).

Remarks.

This species can be distinguished from all other Amasa recorded in Thailand by its small size (2.1 mm long) and stout appearance; elytra approximately as long as the pronotum, and elytral declivity dull, glabrous.

It should be noted that the Afrotropical species, Xyleborus ramulorum Schedl, 1957, included as a synonym of A. cylindrotomica by Wood (1989), Wood and Bright (1992), and Dole and Cognato (2010) is a different species. Xyleborus ramulorum was described and figured from three specimens collected by Schedl in what was then Belgian Congo ( Schedl 1957). Schedl (1963) gave some additional biological information, and figured the gallery system. Nunberg (1963) re-examined the holotype in the Royal Museum for Central Africa, Tervuren, and provided additional morphological characters. He also noted ( Nunberg 1963) that the holotype was badly damaged, and that Schedl had evidently retained undamaged paratypes in his own collection. Browne (1965) transferred the species to Xylosandrus Reitter, 1913. Wood (1989) synonymised this Afrotropical species with the Oriental species, Xylosandrus cylindrotomicus Schedl, 1939, without providing any reason for the synonymy. Dole and Cognato (2010) accepted the synonymy without examining type material, and listed the species as a synonym of Amasa cylindrotomica (Schedl). Examination of an undamaged paratype (NHMW) clearly indicates that the species should be returned to Xylosandrus as a distinct species. Xylosandrus ramulorum stat. res. shares numerous characteristics with Xylosandrus including: mesonotal mycangial tuft present but unlike other Xylosandus the mycangium opening is on the pronotal disc rather than the pronotal base; truncate antennal club with segment 1 encircling the anterior face (type 1; Hulcr et al. 2007); pronotal anterior margin serrate; pronotum from lateral view with disc as long or longer than anterior slope (type 7; Hulcr et al. 2007); and elytral declivity truncate with 5 granulate striae on declivital face, interstriae also granulate. By comparison, Amasa species have the following characteristics ( Hulcr and Smith 2010; Smith et al. in prep.): mesonotal mycangial tuft absent; flat antennal clubs with segment 1 never encircling the anterior face (types 3,4,5; Hulcr et al. 2007), pronotal anterior margin never serrate; pronotum from lateral view basic or robust (types 1 and 5; Hulcr et al. 2007); elytral declivity truncate with no more than 3 punctate striae on declivital face. Ventral characters, including the separation of the procoxae and protibia shape and sculpturing, were not described by Schedl and are not visible on the card mounted paratype. Based on the characteristics listed above, Xyleborus ramulorum is here transferred to Xylosandrus where it shares features with the Asian species included in the Xylosandrus s.l. clade ( Dole and Cognato 2010): X. beesoni Saha, Maiti & Chakraborti, 1992, X. borealis Nobuchi, 1981, X. brevis (Eichhoff, 1877), X. discolor (Blandford, 1898), X. diversipilosus (Eggers, 1941), X. jaintianus (Schedl, 1967), X. subsimilis (Eggers, 1930) and X. subsimiliformis (Eggers, 1939).

Figures

Figure 3. Amasa cylindrotomica (Schedl, 1939) A lateral view B dorsal view C posterolateral view D front E declivity.