Xylechinus

Type species

Hylesinus pilosus Ratzeburg

Adapted from Wood 1982, p. 143-149

Diagnosis

Xylechinus is unique among the Tomicina in having a slightly emarginateemarginate:
notched or indented
or sinuatesinuate:
descriptive of a narrow and winding thin structure or margin of a feature
anterior margin of the eye. In the subtribe, they share the 5-segmented funiclefunicle:
the antennal segments located between the scape and the club in some Coleoptera
only with Dendroctonus Erichson. They have a similar vestiturevestiture:
a surface covering of scales or setae on the body, wing, or other appendage
to Hylorgupinus Swaine but can be distinguished by the number of funiclefunicle:
the antennal segments located between the scape and the club in some Coleoptera
segments.

Description

Species in this genus range from 1.5 to 3.5 mm in length and are approximately 2.0 to 2.4 times as long as wide. Their color ranges from brown to dark brown in species north of Mexico, but it is usually variegated due to light and dark colored scale-like setaescale-like setae:
setae that are wider than hair
vestiture in the Neotropical species. The pronotumpronotum:
the upper or dorsal surface of the first thoracic segment
is usually wider than long, with a few species having it longer than wide, and it is unarmedunarmed:
having no granules, teeth, tubercles, spines, or other protective structures
. The scutellumscutellum:
a shield-like bony plate or scale, as on the thorax of some insects
is small. The declivitydeclivity:
the apical portion of the beetle elytra that slopes downward
is convex, with small granulesgranules:
a small grain-like elevation
and a vestiturevestiture:
a surface covering of scales or setae on the body, wing, or other appendage
of small scale-like setaescale-like setae:
setae that are wider than hair
and sparsesparse:
scattered, spread irregularly and some distance apart
long, light, semi-erect, thick bristles. Their fronsfrons:
the upper anterior portion of the head capsule
usually has a median carinacarina:
a ridge or elevation of the cuticle
above the epistomaepistoma:
the sclerotized region between the lower frontal area and the mouth parts
. The anterior margin of the compound eye is sinuatesinuate:
descriptive of a narrow and winding thin structure or margin of a feature
to slightly emarginateemarginate:
notched or indented
. The scapescape:
the first and basal segment of the insect's antennae
is nearly as long as the 5-segmented funiclefunicle:
the antennal segments located between the scape and the club in some Coleoptera
. The clubclub:
the apical segment of the insect antennae that is enlarged or thickened such that it is anatomically differentiated from the preceding segments
is ovateovate:
egg shaped, with the narrow end apically
and has three straight suturessutures:
a seam or seam-like line of contact between two sclerites or hardened body parts immovably connected
. The prothoracic precoxal ridgeprothoracic precoxal ridge:
an elevated, sclerotized ridge extending from the anterior coxae ventrally towards the head
is either present or absent. The procoxaeprocoxae:
extra segment occasionally preceding coxa (hip joint) of the first or anterior pair of legs of arthropods
are contiguouscontiguous:
sharing an edge or boundary; touching
.

Distribution

Worldwide

World fauna

Number of species: 36, Native species: 2, Introduced species: 0

Hosts

Picea, Oreopanax