Circocerus Motschulsky, 1855

Chandler, Donald S., 2013, Further Notes on the New World Pselaphinae (Coleoptera: Staphylinidae) Described by Victor Motschulsky, The Coleopterists Bulletin 67 (3), pp. 321-327 : 324-325

Circocerus Motschulsky, 1855

Circocerus Motschulsky 1855: 16 . Type species: Circocerus perplexus Motschulsky, 1855 , by monotypy. Type locality: Obispo, Panama.

Apharus Reitter 1882: 130 . Type species: Apharus muelleri Reitter, 1882 , by monotypy. Type locality: Brazil. New synonymy.

Diagnosis. Circocerus is here characterized as having: head with two faint vertexal foveae, antennal club formed by apical three antennomeres, antennomeres IX-X transverse, X approaching basal width of large, apical antennomere; maxillary palpi with apical palpomere enlarged, apical half with large, ovoidal, shallow impression with carinate margins on dorsum. Pronotum with faint, nude, median, antebasal fovea and setose, lateral, antebasal foveae, lacking antebasal, transverse sulcus. Forks of lateral mesosternal foveae elongate and similar in size. Elytra with two basal foveae. First visible abdominal tergite longest, as long as remaining tergites together or longer.

Description. [Based on two specimens cleared and mounted in glycerin in a slide mount: a probable male of C. perplexus from Costa Rica and an unplaced species from Brazil] Head: With 2 faint vertexal foveae; antennomeres II-X transverse, antennal club formed of apical 3 antennomeres, IX-X increasing in width to approach width at base of XI, XI enlarged, asymmetrical in lateral view, slightly humped dorsally, slightly flattened laterally; ocular-mandibular carinae present; gular foveae close in short, transverse impression; fourth maxillary palpus with large, dorsal, ovoidal impression with distinct margins on apical half. Thorax: Pronotum with small, nude, median antebasal fovea, with setose, lateral, antebasal foveae; disc convex, lacking antebasal, transverse sulcus; lateral prosternal foveae present. Median mesosternal foveae with origins close, elongate internally; lateral mesosternal foveae with anterior and posterior forks long, equal in size; lateral mesocoxal foveae present; with single median metasternal fovea. Elytra with 2 basal foveae, lacking discal stria. Abdomen: With tergite 1 elongate, as long as remaining tergites combined, paratergites distinct on tergite 1, variably present/ distinct on tergites 2–3, very narrow when present; tergite 1 with deep basal sulcus, with large mediobasal foveae positioned near lateral margins; tergites 2–4 with very small basolateral foveae or foveae lacking. Ventrite 2 with deep basal sulcus, large mediobasal foveae positioned laterally, ventrites 3–4 with small basolateral foveae. Aedeagus: Symmetrical, with diaphragm; parameres elongate and symmetrical.

Distribution. Members of this genus are found from Mexico to Brazil.

Notes. Six species of Apharus listed by Hlaváč and Chandler (2005) are transferred here, for a total of seven described species. Hamotus clavicornis Reitter (1882) from Venezuela was cited twice by Park (1942): once as H. clavicornis Reitter from Venezuela (p. 329) and also erroneously as Apharus clavicornis Raffray, 1891 ? from Ceará, Brazil (p. 307). This species was subsequently listed as a member of Apharus in Hlaváč and Chandler (2005) and Newton and Chandler (2007), based on confusion in determining generic placements within the Circocerus / Apharus / Upoluna complex and the nominate subgenus of Hamotus . This species is here placed back in the nominate subgenus of Hamotus .