Apical declivity of elytra trituberculate on each side
7
Apical declivity of elytra bituberculate on each side
9
7.
Lateral submargin on apical declivity of elytra very strongly elevated
and acutely, angularly separated at sutural angles; front of head convex in both sexes; antennae densely pubescent
Xyloprista Lesne
8.
Tubercles along anterior margin of apical declivity of elytra costiform,
cylindrical, all obtuse at apices; antenna densely clothed with long hairs; female with front of head flattened or concave, and anterior margin of pronotum with long hairs.
Tubercles along anterior margin of apical declivity of elytra subtriangular, all or at least 1 pair spinose at apices; antenna without, or sparsely clothed with short hairs; female with front of head convex, and anterior margin of pronotum without long hairs
First 2 segments of antennal club elongate, the first subtriangular; female with front of head flattened or concave, and last visible abdominal sternite not emarginate at apex.
First 2 segments of antennal club subrounded or oval; female with front of head convex, and last visible abdominal sternite very deeply emarginate at apex.
This is a photo of Xylobiops basilaris. It is glabrous (no hair) and has reddish spots at the bases of the elytra.This is a photo of Xylobiops sextuberculatus. The elytra are covered with hairs. The same is true for X. texanus.
Key to species of Xylobiops
1.
Dorsal surface of elytra (except apical declivity) without distinct pubescence, the yellow and black or brown areas conspicuously separated
2
Dorsal surface of elytra (except along base) with distinct pubescence, the light and dark-brown areas not conspicuously separated
3
2.
Inner two pairs of tubercles along anterior margins of apical declivity of elytra acute or spinose at apices and coarsely punctured between tubercles, the surface of declivity coarsely, evenly punctured in female, with a few very coarse, deep punctures in male; front of head unarmed
Inner two pair of tubercles along anterior margins of apical declivity of elytra not spinose at apices, and not coarsely punctured between tubercles, the surface of declivity sparsely, finely, irregularly punctate in female, nearly impunctate in male; front of head with two median tubercles in both sexes
Differences between X. texanus and X. sextuberculatus
X. texanus
X. sextuberculatus
Usually has two small tubercles at front of head.
No tubercles in male, 4 to 6 tubercles in female.
Elytra covered with whitish hairs
Elytra covered with brownish hairs
Apical declivity of elytra sparsely, deeply, coarsely, irregularly punctate
Apical declivity of elytra impunctate or very finely punctate
Elytral tubercles spinose at apex except sometimes the sutural one
Elytral tubercles spinose at apex
Abdomen beneath finely, densely, indistinctly granulose or punctate, sparsely clothed with rather long, recumbent, whitish hairs; last visible sternite slightly longer than preceding sternite, and broadly rounded at apex
Abdomen beneath finely, densely granulose or punctate, densely clothed with rather long, recumbent, whitish hairs; last visible sternite twice as long as preceding sternite, and broadly rounded or subtruncate at apex.
Species accounts
Xylobiops basilaris
Male Brownish black to dark reddish brown, with humeri or base of elytra reddish; antennae, palpi, and tarsi brownish yellow, the clypeus often slightly reddish.
Head slightly convex, without distinct median tubercles on front, sometimes longitudinally grooved on front, densely, finely granulose, with fine, longitudinal, parallel costae on occiput, sparsely clothed with short, recumbent, inconspicuous hairs; clypeus vaguely convex, densely, finely granulose, sparsely clothed with short, recumbent, inconspicuous hairs; clypeal suture deeply depressed at middle, obsolete on each side.
Pronotum quadrate or vaguely wider than long, widest along middle; sides vaguely rounded, or parallel along middle, more strongly converging anteriorly, with a short, broad tooth near apical angles; posterior angles broadly rounded; surface sparsely clothed with short, recumbent and semierect inconspicuous hairs on basal half and median part of apical half, and long, erect hairs toward lateral margins on apical half, finely, densely scabrous, with numerous broad, semierect, rasplike teeth on apical half.
Elytra at base subequal in width to pronotum at middle; sides nearly parallel, conjointly broadly rounded at apices; surface glabrous on disk , sparsely clothed with short, recumbent, brownish hairs on apical declivity, coarsely, densely, irregularly punctate on basal two thirds; apical declivity with a few large, deep, foveolate punctures on each side and between tubercles, smooth along sutural margins, which are slightly, broadly elevated, the lateral margins strongly elevated; each elytron with two or three short, broadly rounded, smooth costae at base, and with three costiform tubercles along anterior margin of apical declivity, the tubercles rather short, and acute at apices.
Abdomen beneath densely, finely granulose, indistinctly punctate, rather densely clothed with short, recumbent, whitish hairs, with a few long, erect hairs on last visible sternite, which is broadly subtruncate at apex.
Female Differs from the male in having the last visible abdominal sternite slightly longer, and feebly, narrowly emarginate at the apex, and the punctures on the apical declivity of the elytra smaller, more numerous, and distributed over nearly all of the surface.
Length 4-7mm, width 1.5-2.5mm
Xylobiops parilis
Description temporarily omitted, because it seems this species is known mainly from Mexico, possibly also southern California and Arizona. Sometimes imported as infestation in bamboo.
Xylobiops texanus
Male Reddish brown, sometimes with the head, pronotum in part, and apex of elytra darker; antennae, palpi, anterior coxae, last visible abdominal sternite, and legs (except anterior tibiae) brownish yellow.
Head slightly convex, usually with two small, median tubercles on front, densely, finely granulose, with a few larger granules intermixed on front, with fine, longitudinal, parallel costae on occiput, sparsely clothed with short, recumbent, inconspicuous hairs, with a few longer, erect hairs intermixed; clypeus nearly flat, densely, shallowly punctate, sparsely clothed with short, recumbent, inconspicuous hairs; clypeal suture deeply depressed at middle, obsolete at sides.
Pronotum quadrate or slightly wider than long, widest along middle; sides vaguely rounded or parallel along middle, more strongly converging anteriorly; apical and posterior angles broadly rounded; surface sparsely clothed with short, recumbent, inconspicuous hairs, with numerous long, erect hairs on apical half toward lateral margins, sparsely, indistinctly punctate at sides, finely, densely granulose on median part of basal half, densely, irregularly dentate on apical half, the teeth broad, semierect, variable in size, and rasplike.
Elytra at base subequal in width to pronotum along middle; sides nearly parallel, conjointly broadly rounded at apices; surface densely clothed with short, recumbent, whitish hairs, except sometimes at base, rather densely, coarsely, irregularly, shallowly punctate on disk; apical declivity sparsely, deeply, coarsely, irregularly punctate, the sutural margins slightly, broadly elevated, and lateral margins strongly elevated; each elytron with vaguely indicated costae at base, and with three costiform tubercles along anterior margin of apical declivity, the tubercles (except sometimes the sutural one) spinose at apices
Abdomen beneath finely, densely, indistinctly granulose or punctate, sparsely clothed with rather long, recumbent, whitish hairs; last visible sternite slightly longer than preceding sternite, and broadly rounded at apex
Female Differs from the male in having the last visible abdominal sternite twice as long as the preceding sternite, and the apical declivity of the elytra not so deeply depressed.
Length 3-5mm, width 1-1.9mm
Xylobiops sextuberculatus
Male Brownish or reddish black; elytra reddish brown, sometimes paler at base; antennae, palpi, and legs (except anterior tibiae) brownish yellow.
Head slightly convex, unarmed and densely, finely granulose on front, with fine, longitudinal, parallel costae on occiput, sparsely clothed with short, recumbent, inconspicuous hairs, with a few long, erect hairs intermixed; clypeus vaguely convex, densely, shallowly punctate, sparsely clothed with short, recumbent, inconspicuous hairs; clypeal suture deeply depressed at middle, obsolete at sides.
Pronotum slightly wider than long, widest along middle; sides nearly parallel or vaguely rounded along middle, more strongly converging anteriorly; apical and posterior angles broadly rounded; surface sparsely clothed with short, recumbent, inconspicuous hairs, with a few long, erect hairs on apical half toward lateral margins, finely, sparsely, indistinctly punctate at sides, densely, finely scabrous at middle on basal half, densely, irregularly dentate on apical half, the teeth broad, semierect, variable in size, and rasplike
Elytra at base subequal in width to pronotum along middle; sides nearly parallel, conjointly broadly rounded at apices; surface densely clothed with short, recumbent, brownish hairs, except at base, densely, rather coarsely, shallowly punctate on disk; apical declivity impunctate or very finely punctate, the sutural margins slightly, broadly elevated, and lateral margins very strongly elevated; each elytron with three more or less distinct, longitudinal costae, and with three costiform tubercles along anterior margin of apical declivity, the tubercles long, and spinose at apices.
Abdomen beneath finely, densely granulose or punctate, densely clothed with rather long, recumbent, whitish hairs; last visible sternite twice as long as preceding sternite, and broadly rounded or subtruncate at apex.
Female Differs from the male in having four to six distinct tubercles on the front of the head, and the last visible abdominal sternite as long as the preceding two sternites united, transversely, arcuately carinate at the middle, and produced into a lobe, which is obtusely rounded at the apex.
Length 3-5mm, width 1.4-1.75mm
Footnotes:
This document is an excerpt from A Revision of the North American Species of Beetles Belonging to the Family Bostrichidae by W. S. Fisher, April 1950, published by the US Department of Agriculture.
