Oropodes Casey, 1894

Chandler, Donald S. & Caterino, Michael S., 2011, A taxonomic revision of the New World genus Oropodes Casey (Coleoptera, Staphylinidae, Pselaphinae), ZooKeys 147, pp. 425-477 : 426-432

Genus Oropodes Casey, 1894

Oropodes Casey, 1894: 453. Type species: Oropodes orbiceps Casey, by monotypy. Raffray 1898: 211 (key), 246; 1904: 526 (key), 565; 1908: 41 (key), 81; 1911: 27. Bowman 1934: 8 (key), 25. Arnett 1960: 315 (key), 321. Park and Wagner 1962: 15. Grigarick and Schuster 1976:97 (revision); 1980: 27, pl. 29. Newton and Chandler 1989: 23 (catalog). Chandler 1990: 1187 (key); 1997: 15 (catalog); 2000: 290 (key), 347; 2001: 107; 2002: 57 (key), 79.

Description.

Dorsal habitus as in Figure 1. Length 1.68-2.40. Body light yellow-brown to brown. Head trapezoidal, narrowing apically, slightly narrower than pron otum, base nearly straight, vertexal foveae nude, connected by an inverted U-shaped sulcus; with prominent rounded antennal tubercles, lacking interantennal ridge; with 11 antennomeres, IX-XI forming loose club, X symmetrical and usually wider than IX, antennomeres V and VII usually slightly larger than adjacent antennomeres; head venter with short sparse setae angled anteriorly, with faint median gular suture, single gular fovea at head base, with gular boss at base of mentum.

Pronotal disc with shallow median longitudinal sulcus extending to base, lateral longitudinal sulci faint to indistinct; antebasal sulcus deep, forming a broad V between nude lateral antebasal foveae, lacking median antebasal fovea; lateral margins convergent basally, carinate in basal half, slightly constricted adjacent to lateral foveae, margins denticulate from constriction to base; base with lateral margins polished, forming two vague oval impressions to each side. Prosternum convex, with lateral prosternal carinae extending from anterolateral corner of procoxae obliquely dorsally to cervix; lateral procoxal foveae present.

Elytra with 3 basal foveae, short discal stria extending from lateral foveae no more than one-third elytral length; with subhumeral fovea; with apicolateral cleft. Median mesosternal fovea broadly forked from single opening, lateral mesosternal foveae broadly forked, anterior fork small and isolated; lateral mesocoxal foveae present; lacking metasternal foveae. Hindwings fully developed.

Abdomen with visible tergites 1-3 subequal in length, 4 slightly longer; 1 with basolateral foveae, deep depression between foveae nude, anterior face of depression with two large blunt teeth facing posteriorly; tergites lacking discal carinae at base. Metacoxal cavities angularly prolonged posteriorly near mesal margin; first visible ventrite usually with short carinae extending posteriorly from apex of angulation to ventrite apex, medial area between carinae flat or nearly so; second ventrite with inner and outer basolateral foveae in setose basolateral sulci. Profemora lacking ventral sensory pits or impression; tibiae with apical ctenidia of few to several spines on anterior and posterior margins.

Males with third ventrite bearing median anteriorly-directed lamina. Aedeagus with dorsal diaphragm; parameres asymmetric, flattened and fused at base.

Biology.

Specimens of Oropodes have been taken in the widest array of habitats possible for pselaphines in California, ranging from redwood forests, high elevation Douglas-fir forests, gallery forests in grassland areas, dry chaparral/ pine forests, foothill woodlands, grass roots, an urban residential area, and from a cave in an area of high desert scrub. Many of the species have been found at sites dominated by dry pine/oak forests mixed with brush or chaparral. Use of passive traps (light traps, flight intercept traps) in southern half of California have been the most productive techniques in collecting species, as species have been difficult to find by the usual procedure of berlesing leaf litter or root mat samples.

Adults seasonality exhibits two broad patterns: the species from northern California, where rain is received during the summer, have collection records from months throughout the year. Those species occurring where there are long periods without rain, particularly those from southern California, appear in late autumn and early winter, and may be taken until June when the California summer is well under way.

Relationships.

Oropodes is certainly close to Euplecterga Park & Wagner, 1962, being effectively the sister-group in view of the latter genus being initially described as a subgenus of Oropodes . They are similar in habitus, sharing the somewhat flattened body, the slightly enlarged seventh antennomere, the shallow median sulcus of the pronotum, the abdominal tergites subequal in length, and with the males possessing a median lamina on the third ventrite and lacking sensory pits on the profemora. The two genera are separated by the presence of promesocoxal foveae, the lack of inner basolateral foveae on the second ventrite, the first ventrite lacking longitudinal carinae arising at the posteromedial angulations of the metacoxal cavities, and the asymmetrical male eleventh antennomere for Euplecterga , while Oropodes lacks promesocoxal foveae, both inner and outer basolateral foveae are present on the second ventrite, nearly all species have distinct longitudinal carinae arising at the posteromedial angulations of the metacoxal cavities that extend posteriorly to the apex of the first ventrite, and the male eleventh antennomere is symmetrical. The two genera are indeed similar in overall appearance, and a single specimen from the San Francisco Bay area was in the process of being treated as an undescribed species of Oropodes before the first author fortunately realized it was the second known specimen of Euplecterga fideli Grigarick & Schuster (1976). The male holotype of Euplecterga fideli was collected in Santa Cruz County, 9 mi NE of Soquel, while the newly discovered male has the data: San Mateo County, Lake Pilarcitos, III-20-1965, C.W. & L.B. O’Brien, shore debris (CNCI)].

The mesosternal foveal pattern places these two genera clearly in the subtribe Trichonychina ( Chandler 2001: 107). Grigarick and Schuster (1980: 25) produced a tree for the twelve North and Central American genera in their "Group B" (= Trichonychina ) indicating two major clusters of genera based on a few characters, with a group holding the genera Bontomtes Grigarick & Schuster and Foveoscapha Park & Wagner being placed adjacent to Oropodes in one major cluster, and Euplecterga associated with Tetrascapha Schuster & Marsh in the other major cluster. The subequal lengths of the abdominal tergites, lack of lateral metasternal foveae, and the somewhat flattened body are features found only in Oropodes and Euplecterga amongst these genera (metasternal foveae lacking in Tetrascapha ), while the sulcate pronotal disc is shared with Bontomtes and Foveoscapha . These last two genera are more robust in appearance and the lateral metasternal foveae are present.

Within the genus the species are placed into three preliminary species-groups: the arcaps-group (4 species), the orbiceps-group (4 species), and the raffrayi-group (10 species). In the taxonomic section the species-groups are treated alphabetically, with the included species of each group similarly treated alphabetically.

Keys to species of Oropodes .

Males may be identified using the secondary sexual characters of the legs, abdominal lamina, apical sclerites, and genitalia, while females have valuable characters on the apical sclerites of the abdomen and the internal genitalia. Due to the possibility of encountering undescribed species we advise that the genitalia be extracted, mace rated, and viewed. Also, the leg characters of the male tibiae may be obscured by dense setae, and are difficult to see unless placed on a slide in a glycerin mount. Caution is urged when identifying isolated females. Females are not known for six of the species described here, and we have seen seven female morphospecies with distinctive genitalia that lack associated males. Males always have a recurved lamina following an impression at the middle portion of the third ventrite, and at least the second ventrite is medially impressed. Females lack the lamina on the third ventrite, which together with the second ventrite are both convexly and evenly rounded.

Key to males.

Key to females.

Unassociated female specimens with distinctive genitalia.

The unassociated females we have seen are listed here so that the specimens may be located by future workers. Five are represented by single specimens.

1) Fresno County: 9 mi E Coalinga, III-20/VI-4-1981, Gilbert & Andrews (CSCA, 2 specimens).

2) Fresno County: Sequoia National Forest, 3 mi W Cedar Grove, 4400', V-14-1976, A. Newton & M. Thayer (FMNH).

3) Los Angeles County: Point Mugu State Park, Boney Mountain State Wilderness, 34.1354°N, 118.9524°W, V-3-2009, M.S. Caterino & K.J. Hopp, Umbellularia / Platanus litter (SBMN, 2 specimens).

4) Madera or Mariposa County: Ahwahnee, May, A. Fenyes Collection (CASC). [either Ahwahnee, town in Madera County, 37.3639°N, 119.7203°W; or Ahwahnee Lodge in Yosemite Valley (Mariposa County), 37.7458°N, 119.5742°W]

5) Santa Barbara County: LPNF [Los Padres National Forest], Oso Canyon, IV-28-2002, M. Caterino (SBMN).

6) Tehama County: 6 mi SE Manton, Soap Creek, 716 m, XII-4-1991, D. S. Chandler, sift willow/mixed litter by stream (DSC).

7) Tulare County: Ash Mountain Power Station, XI-23-1982, J.A. Halstead (CNCI).

The arcaps-group.

Included species: Oropodes arcaps Grigarick & Shuster, Oropodes dybasi Park & Wagner, Oropodes ishii Chandler, and O. yollabolly Chandler.

Diagnostic features: Eyes relatively small, 12-40 facets. Males lacking basal spine on venter of profemora; second ventrite with posterior margin smooth, lacking teeth or lobes. Females with transverse margins of setose area of fifth ventrite parallel; genitalia with membranous lobe symmetrical or nearly so.

Geographical distribution: The range of this group extends from north of the San Francisco Bay area of California into Oregon (Map 1).