Stenosphenus lugens Click here for a larger view

Diagnosis.--Key characters: Ommatidial size fine (Fig. 39a); transverse ridges on pronotal disc absent; raised ivory calli on elytra absent; femoral carinae absent; femoral apices rounded (Fig. 26); tibial carinae present (Fig. 22); lateral projecions into mesocoxae from mesosternum present (Fig. 21); procoxal cavities open posteriorly (Fig. 18); median pronotal callus absent; long, coarse, erect setae absent; elytra without large, pale maculations (unicolorous in most specimens); elytra varying from truncate to weakly spinose at apices; elytral apices not narrowed or acuminate; femora gradually enlarged (Fig. 37c); third antennomere about one and one-half times length of fourth; bottom margin of metepisternum approximately parallel to margin of elytra above it (Fig. 33). Length: 8-20 mm.

Distribution and Diversity.--Continental United States to Costa Rica. Twenty-three species.

Discussion.--Stenosphenus is very closely related to Ironeus, based on the implied weighting analysis (Fig. 50). Tropimerus is probably very closely related also, but could not be included in the analysis.

The finely-faceted eyes, bright coloration and diurnal activity separate Stenosphenus from most other elaphidionine genera. It differs from Tropimerus in lacking mesofemoral carinae. Stenosphenus differs from Ironeus in having a metepisternum approximately parallel to elytral margin (bottom margin of metepisternum in Ironeus angling up and intersecting elytra towards posterior end). Stenosphenus is separated from Ironeus also by its tapering facies and anteriorly rounded and constricted pronotum.