Acerocephala Gahan, 1946

Honsberger, David N., Honsberger, Maya, Lorenzo-Elarco, J. Hau‘oli & Wright, Mark G., 2024, The genus Acerocephala and observations of the life history of Acerocephala hanuuanamu sp. nov. (Hymenoptera, Cerocephalidae) and its bark beetle host on the island of O‘ahu, Hawai‘i, Journal of Hymenoptera Research 97, pp. 545-589 : 545-589

Acerocephala Gahan, 1946

Redescription.

Head subrectangular in face view, somewhat thin and elongate in side view, flattened dorsoventrally and not globose (vac. l / hea. l approximately 1.7 or greater). Anterolateral corner of head a distinct angle, sides of face either progressively widening to this corner or mildly curved mesally to reach it. Mandibles long and arcing (mdb. l / hea. b approximately 0.5 or greater), placed widely on face, their lateral corners at or nearly at anterolateral corners of face. Anterior of face a concave arc; clypeus, which has its base near the ventral side of this arc, may be visible in dorsal view projecting into the space between the mandibles. Compound eyes placed nearer back of head than front, so that vey. l / vac. l ≤ 0.5. Antennae inserted well anterior of compound eye, funicle with 5 or 6 segments in female. Scrobes deep and extend posteriorly well behind toruli. Scrobes separated by interantennal ridge that extends well behind the toruli to join with the upper face, the ridge flattened or mildly curved dorsally and protruding or not from plane of the face.

Forewing with or without callus on parastigma, but the callus, if present, without a tuft of setae. Wing membrane with slightly rippled texture and without setae on its surface; stigmal vein short, postmarginal vein short if present. Males of some species may be wingless.

Diagnosis and differential diagnosis.

This genus can be distinguished within Cerocephalidae by the combination of elongate rectangular, thin head shape (vac. l / hea. l ≥ 1.7); anterolateral corner of face a distinct angle, and with long mandibles placed with their outer edges near the anterolateral corner of the face; antennae inserted distinctly anterior of compound eye; forewing without a tuft of thick setae on callus on the parastigma, or lacking a callus, and without setae extending from its membrane; clypeus may project into space between mandibles from near ventral side of arc that comprises the anterior of the face, dorsal plane of head lacking a distinct anterior projection into space between mandibles.

Within Cerocephalidae , this genus appears closest to Choetospilisca (Fig. 9 ), Paralaesthia , and Muesebeckisia . It can be distinguished from Choetospilisca by the elongate rectangular shape of the head in dorsal view and long arcing mandibles extending from just inside the anterolateral corner of face; and broad interantennal ridge joining to the plane of the upper face. ( Choetospilisca with head more globose in side view; face broadly tapers anteriorly, and thick but shorter mandibles extending from well inside the lateral edge). The overall shape of the face is similar to Paralaesthia , but it can be distinguished by the lack of a tuft of thick setae on the callus of the parastigma; at most a small projection of the clypeus into the space between the mandibles, which has its base on the ventral side of the arc that comprises the front of the face; scrobal grooves posterior to toruli deep and separated by a large, broad interantennal ridge connecting to the upper face; lack of a mesal groove on the upper face; funicle segments slightly nodose-bead like or transverse ( Paralaesthia with thick setae emerging from the callus; lower face anteriorly extended into a large triangular region between the mandibles, its base extending from the dorsal plane of the face; a mesal groove running the length of the upper face; scrobes shallow and not extended greatly posterior to toruli, interantennal ridge small and similarly not of much consequence posterior to toruli; funicle segments elongate cylindrical). It can be distinguished from Muesebeckisia by the more elongate head shape and location of antennal insertion well below the anterior margin of the eyes, and broad interantennal ridge. ( Muesebeckisia with head globose, eye reaching the anterior half of the face, and antennal insertion above anterior margin of eye).

Figures

Figure 9. Choetospilisca tabida holotype ♀ (a – e) and allotype ♂ (f – i) a, f side view b, i dorsal view c antenna d, g head e, h anterior view of head showing mandibles.