Stenotrupis tenuis, Zimmerman, 1942

Zimmerman, Elwood C., 1942, Curculionidae of Guam, Insects of Guam I, Honolulu, Hawaii: Bernice P. Bishop Museum, pp. 73-146 : 126-127

33. Stenotrupis tenuis , new species (pl. 5, D).

Female. Derm rather uniform reddish brown, rather shiny, at least in part somewhat translucent.

Head slightly longer than broad, post-ocular constriction distinct, not so deeply impressed across dorsum as on sides and below; smooth and shiny, evidently not punctate behind constriction, minutely punctate beyond constriction, punctures separated by distances equal to or g-reater than their diameters; eyes subcontinuous in lateral outline with head, when measured from above, separated from the post-ocular constriction by twice the length of an eye, interocular area longitudinally evenly convex, twice as broad as an eye as measured from above. Rostrum just perceptibly longer than pronotum (21: 19), evenly arcuate longitudinally, narrowed on sides from base to about half way to antennae, then almost evenly expanded to antennae, thence slightly and evenly narrowed to about half way between antennae and apex, thence more rapidly enlarged to the apex, greatest apical breadth almost twice that of narrowest breadth between antennae and apex and equal to basal breadth at eyes; minutely punctate, smooth and shiny;.antennae inserted at about basal fourth, distance between the insertion and eye twice longitudinal diameter of an eye as measured from side; scrobes evanescent behind. Antennae with scape reaching to middle of eye; first funicular segment as long· as 2 plus 3, 2 longer than broad, 3 to 5 successively broader; club not as long as four preceding segments. Prothorax not qtiite one fourth longer than broad (1.5: 1.9), broadest at about basal third, sub-pyriform, without a distinct subapical constriction, longitudinal dorsal outline flat from base to apex; disk minutely punctate, punctures separated by smooth, shiny interstices as broad or broader than punctures. Elytra more than three times as long as broad (4.3: 1.6), slightly more than twice as long as prothorax (4.3: 1.9), subparallel-sided in about basal three fourths; striae fine and shallow, their punctures close, crenulating sides of intervals and about as· broad as intervals; intervals rather shiny, evidently without setae except on declivity and there with numerous, long, erect hairs. Legs with tibial unci well developed and with a tooth at front and hind edges of inner apical angles; third tarsal segment not bilobed, hardly broader than second. Sternum finely.alutaceous, prosternum about three times as long as longitudinal diameter of a coxa in front of coxae and about twice as long as a coxa behind, at most minutely punctate, intercoxal process about four fifths as broad as a coxa; mesocoxae separated by about one and one fourth times breadth of a coxa; metasternum more densely and distinctly punctate at sides than in middle and with short, fine hairlike setae on more densely punctate areas, about four times as long between mid and hind coxae as breadth of a mesocoxa, metacoxae one half as widely separated as mesocoxae. Venter tumid, minutely punctate; setae distinct only at sides and on fifth ventrite; sutures arcuate; fifth ventrite densely punctate. Length, 1.5 mm.; breadth, 0.4 mm.

Holotype female taken at Yigo, from rotten stump, Nov. 13, 1936, Swezey .

This small species may be distinguished by the combination of its rather shiny derm, long slender rostrum, the antennae inserted at twice the length of an eye beyond the eyes and the long hairs at the apex of the elytra. It has in the long hairs on the elytra a character in common with the Hawaiian Stenotrupis pritchardiae (Perkins) (= Pentarthrum pritchardiae Perkins, B. P. Bishop I. VIus., Bull. 31: 57, 1926, from Nihoa), but S. pritchardiae is a very different insect and not allied to this species. The distance between the eyes and the insertion of the antennae on S. tenuis is unusually great, and is not found on any of the other species known to me, most of which have the antennae inserted in the rostrum at no greater distance from the eyes than the length of an eye.

In addition to the holotype of this species, there is another specimen of Stenotrupis , which was taken at light at Piti, July 5, 1936 by Swezey ; the status of this specimen I cannot determine without additional material. It is much like the holotype, but has some striking differences, some of which might be taken as sexual. However, the specimen is, I believe, also a female, as it has a typical female rostrum and abdomen. The most outstanding difference between the two specimens is that this unnamed example has the antennae inserted at only about the length of an eye in front of the eyes instead of much more distantly. It also has the cephalic constriction deeper than on S. tenu.is and the area in front of the constriction is more coarsely punctate. Only a larger series containing both sexes will enable me to decide whether this specimen represents a new species or is but a form of S. tenuis .