Hylastinus

Type species

Ips obscurus Marsham

Adapted from Wood 1982, p. 108-110

Diagnosis

In general, North American Hylesinina are similar to Scierus LeConte in the Hylastina, but their procoxaeprocoxae:
extra segment occasionally preceding coxa (hip joint) of the first or anterior pair of legs of arthropods
are less widely separated than in that genus. Among them, they can be easily distinguished by characters of the anterior margin of the eye which is entire in Hylastinus Bedel, sinuatesinuate:
descriptive of a narrow and winding thin structure or margin of a feature
in Hylesinus Fabricius, and emarginateemarginate:
notched or indented
in Alniphagus Swaine. Hylastinus’ anterior margin crenulationscrenulations:
structures on the surface of the integument an having irregular, wavy, or serrate outline
form a single row of small teeth.

Description

Species in this genus range between 2.0 to 2.5 mm and are approximately 2.2 times as long as wide. Their color is usually dark brown. The pronotumpronotum:
the upper or dorsal surface of the first thoracic segment
of the single species occurring in the USA is wider than long. The scutellumscutellum:
a shield-like bony plate or scale, as on the thorax of some insects
is small and depresseddepressed:
a structure that is flattened or impressed
. The anterior margin of the elytraelytra:
the two external and hardened or sclerotized forewings of adult Coleoptera, often appearing leather-like in texture
is armedarmed:
having a sclerotized surface structure, giving a rough texture; may serve as defense
by a single row of crenulationscrenulations:
structures on the surface of the integument an having irregular, wavy, or serrate outline
extending to striaestriae:
longitudinally arranged lines often impressed or marked by punctures that are located between the interstriae on the Coleopteran elytron
nine. The declivitydeclivity:
the apical portion of the beetle elytra that slopes downward
is convex, usually bears granulesgranules:
a small grain-like elevation
, and has a hair-like vestiturevestiture:
a surface covering of scales or setae on the body, wing, or other appendage
. The anterior margin of the compound eye is entire. The scapescape:
the first and basal segment of the insect's antennae
is usually as long as the 7-segmented funiclefunicle:
the antennal segments located between the scape and the club in some Coleoptera
. The ovateovate:
egg shaped, with the narrow end apically
clubclub:
the apical segment of the insect antennae that is enlarged or thickened such that it is anatomically differentiated from the preceding segments
has three straight suturessutures:
a seam or seam-like line of contact between two sclerites or hardened body parts immovably connected
. The prothoracic intercoxal pieceprothoracic intercoxal piece:
a ventral, often triangular, sclerite of the prothorax that extends posteriorly between the anterior coxae
is wide and margined on the side in front of the coxaecoxae:
the basal or proximal segment of the insect leg to its body
by a long, elevated ridge that extends from the subcontiguoussubcontiguous:
pertaining to adjacent structures, margins, or surfaces that are in contact but are not united or fused
coxaecoxae:
the basal or proximal segment of the insect leg to its body
to the anterior margin.

Distribution

Four European species are known, one of which has been introduced into North America

World fauna

Number of species: 4, Native species: 0, Introduced species: 1

Established exotic species

Hylastinus obscurus is present in Vermont, Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Maryland, Virginia, Indiana, Michigan, Wisconsin, Montana, Idaho, Washington, Oregon, Utah, and California.

Hosts

Lathynts, Medicago, Melilotus, Trifolium, Vicia