Custotychus Park and Wagner, 1962

Chandler, Donald S. & Geromini, Sarah D., 1962, A Revision of the Eastern Nearctic GenusCustotychusPark and Wagner, 1962 (Coleoptera: Staphylinidae: Pselaphinae), The Coleopterists Bulletin 1962 (2), pp. 217-242 : 217-242

Custotychus Park and Wagner, 1962

Tychus auctorum (in part): LeConte 1849: 82, 1863: 21; Schaufuss 1888: 94; Casey 1894: 491, 1897: 615; Raffray 1904: 295, 1908: 293, 1911: 131; Leng 1920: 131; Bowman 1934: 118; Brimley 1938: 149; Park 1949: 327, 1956: 95; Downie and Arnett 1996: 589.

Lucifotychus (Custotychus) Park and Wagner 1962: 23 . Type species: Tychus daggyi Park by original designation. Grigarick and Schuster 1962: 169; Newton and Chandler 1989: 53.

Custotychus Park and Wagner : Chandler 1988: 158 (redescription), 1990: 1183 (key to genera), 1991: 47, 1997: 79 (catalog), 2000: 294, 352; Poole and Gentili 1996: 396; Kurbatov and Sabella 2008: 55.

Description. Body 1.52–1.94 mm long. General habitus as in Fig. 1 . Head with vertexal foveae small, about 4 foveal diameters medial to compound eyes, nearly dorsal in position; with single gular fovea; antennal bases close, inserted on distinct rostrum; with small, acute spicule to each side of vertex between antennal tubercles and eyes; antennomeres IX–X strongly transverse, nearly twice as wide as long; 3 rd maxillary palpomere elongate, rounded-angulate on mesal margin, often appearing more acutely angulate due to setal tuft ( Fig. 32 ). Prothorax with lateral prosternal foveae, pronotum lacking antebasal sulcus and foveae, with 5 small, nude basal foveae. Elytra with 2 basal foveae. Thorax with 2 lateral and medial mesosternal foveae, lateral mesosternal foveae sometimes divided for short distance at apices; with widely separated metasternal foveae. Abdomen with tergite 1 bearing mediobasal foveae, lacking discal carinae, tergites 1–4 with basolateral foveae; ventrite 1 with intercoxal process widely separating metacoxae; ventrite 2 with deep setose basal sulcus, with 2 close mediobasal foveae, with basolateral foveae; ventrites 3–5 with remnants of basolateral foveae. Males with protrochanters simple, protibiae lacking spur, mesotrochanters simple, mesotibiae with apical and preapical spurs, apical spur broad, with widely separated apical spines, metatrochanters simple, metatibiae with acute, apical spur, metasternum with median tubercle; aedeagus symmetrical, basal bulb large, ovoidal in dorsal view, with free dorsal plate and fixed ventral lobe, dorsal plate with large lateral arms, often with median portion distinct and protruding ventrally, phallobase diaphragm absent; parameres present, often weakly sclerotized.

Remarks. Grigarick and Schuster (1962) briefly commented that the subgenus Custotychus should be recognized at the generic level without formally proposing this, and they indicated that Park and Wagner (1962) had included all of the eastern species of Lucifotychus in this subgenus. However, they had only mentioned the type species, T. daggyi , in their description. Chandler (1988) formally placed Custotychus at the generic level and added the following species: Tychus minor LeConte, 1849 ; Tychus spiculifer Casey, 1894 ; Tychus verticalis Casey, 1894 ; and Tychus pocahontas Casey, 1897 . All members of this genus are found only in the eastern United States. Custotychus shares with Atychodea Reitter (Southeast Asia) the derived apical and subapical spurs of the mesotibiae and the primitive presence of the mediobasal foveae of sternite II. The two genera are separated by the derived lack of a phallobase diaphragm, presence of two elytral foveae, and lack of a median antebasal fovea on the pronotum in Custotychus , while Atychodea has a phallobase diaphragm, 3–4 elytral foveae, and a median antebasal fovea on the pronotum ( Chandler 1988; Kurbatov and Sabella 2008).

Collection Techniques. Members of all species are fully winged, and a number of species have been taken based on their attraction to ultraviolet or mercury vapor light, particularly C. minor . A few have been taken by pitfall and flight intercept traps, but most have been extracted from forest leaf litter by use of Berlese funnels. The predominate source is hardwood leaf litter, particularly beech, magnolia, sweetgum, maple, and oak leaf litters, and occasionally from pine litter. Specimens are taken infrequently from rotten stumps or woody debris, and one species, C. watrousi new species, was taken primarily from beneath bark (based on one large sample). Another species, C. leei new species, was commonly taken from tree mosses ( Climacium americanum Brid. , Climaciaceae ), which grow at the bases of trees in the mesic woods of northern Ohio.

Figures

Figs. 1–7. Custotychus species. 1) C. natchez, dorsal habitus; 2–7) Aedeagus, dorsal and left lateral views:

Figs. 28–32. Custotychus species. 28) C. pocahontas, scanning electron micrographs of right lateral (a) and posterior (b) views of metasternal tubercle. Grid for measurements of 20 or 50m at bottom of micrographs; 29) C. carloritaorum, mesotibial spurs; 30) C. spinosus, mesotibial spurs; 31) C. watrousi, abdominal ventrites, ventrolateral view; 32) C. daggyi, right maxillary palpus, ventral view. Scale bar = 0.1 mm.