Microcryptorhynchus premnae, Zimmerman., 1942

Zimmerman, Elwood C., 1942, Curculionidae of Guam, Insects of Guam I, Honolulu, Hawaii: Bernice P. Bishop Museum, pp. 73-146 : 116-117

26. Microcryptorhynchus premnae , new species (pl. 3 H).

Derm shiny black when exposed, with antennae and tarsi reddish, covered with a thin to moderately dense gray incrustation; setae mostly white, but with some dark ones on dorsum.

Head narrowly exposed from above, coarsely reticulate, indistinctly punctate, with small round, rather obscure squamae, with one or two rows of broad, erect spatulate setae extending from rostrum along inner margins of eyes and scattered on front above level of eyes. Rostrum setose and encrusted only at base in female, the three dorsal carinae well defined to antennae, median one becoming evenly broader distad, minutely punctate and thinutely setose beyond antennae, with two rows, sometimes three near the base, of broad, spatulate, erect setae and encrusted from base to antennae in male, carinae obscured except near antennae. Prothora:. one fifth broader than long, strongly rounded on sides from base to subapical constriction at about apical third, constriction continued shallowly and broadly across dorsum, basal squamose area unmodified; dorsal puncturation very dense, punctures not large, but coarse, surface having an asperate appearance when abraded; with an irregular, variable, complete or vestigial, narrow, bare median carina; closely set with conspicuous, erect, clavate, and spatulate setae. Elytra stoutly ovate, over three fifths as broad as long (3.5: 5), almost to distinctly two and one half times as long as prothorax, broadly arcuate on sides from base to apex, without a subapical constriction, longitudinal dorsal outline arcuate before steep declivity, reaching its summit at middle and there not greatly elevated above level of pronotum; stria! punctures quadrate, large and coarse, as broad or broader than intervals, their interstices narrower than their lengths; intervals slightly convex, each bearing a row of conspicuous, erect, broad, spatulate setae. Legs with femora with scattered, erect, spatulate setae; tibiae with prostrate matted hair and rows of erect spatulate setae, uncus arising from outer apical angle and well developed throughout. Stermtm with mesosternal receptacle deep and cavernous, terminating at about middle of mesocoxae in male and almost at their apices in female, hind wall twice as thick in male as in female, but slightly protuberant; metasternum coarsely punctate, about half as long between mid and hind coxae as breadth of a mesocoxa; metacoxae separated by a distance slightly more than twice that of length of metasternum along median line. Venter with scattered setae, the first two ventrites coarsely and densely punctured, the first flattened and similar in both sexes, intercoxal process subtruncate in middle but rounded at corners; ventrite 5 coarsely reticulate, not distinctly punctured. Length, 1.3-1.75 mm.; breadth, 0.75-0.9mm.

Holotype male, to be deposited in National Museum , aIIotype female, in Bishop Museum, 28 paratypes , one broken specimen and one dissected specimen coIIected from Premna gaudichaudii , July 23, 1937, Oakley , no. 37-24080.

This species is very closely aIIied to M. guamae but is narrower and not so strongly inflated, the prothorax is not so transverse, has the subapical constriction less deep and a distinct, although very variable, median carina; the incrustation is grayer; the elytra are not so globose and not so strongly convex dorsally; the male genitalia are quite distinct from M. guamae . The variable median carina of the prothorax is perhaps the best external character to use in separating this species from M. guamae . This species has a distinct facies because of its different proportions of the body that should enable one to segregate specimens of it from a series of the two species without great difficulty, in spite of the great similarity of this and M. guamae .

The outstanding differences exhibited in the structure of the male genitalia of these two closely allied species is particularly noteworthy. The external characters of the two species are, for the most part, quite similar, but the male aedeagus is most distinct on each.