Trogastrina Jeannel, 1949

Owens, Brittany E. & Carlton, Christopher E., 2016, Collecting in the Museum: New Species, Taxonomic Changes, and Range Extensions of Euplectite Pselaphinae (Coleoptera: Staphylinidae) of the Southeastern United States, The Coleopterists Bulletin 70 (3), pp. 611-633 : 611-633

Subtribe Trogastrina Jeannel Conoplectus Brendel, 1888

Diagnosis. Males. Head: Transverse, abruptly constricted into short cervical region that inserts into prothorax, frons modified, possessing horn, declivity, and/or degrees of excavation of transverse frontal sulcus; gular area convex, bearing dense genal beard; antennae clavate, acetabula distant. Thorax: Pronotum rounded, obcordate, bearing midlongitudinal shallow sulcus and antebasal transverse sulcus, basolateral foveae present, prosternum slightly concave, median prosternal foveae present; mesoventrite bearing median and lateral mesoventral fovea; posterior mesocoxal foveae present; all coxae contiguous, legs unmodified; elytra with sutural fovea and striae, antebasal discal foveae and subhumeral foveae present, discal striae present; wings present. Abdomen: Small antebasal foveae present on each visible tergite, tergite II with longitudinal basal carinae separated by transverse pubescent depression, other tergites unmodified; ventrites III–VI variable (excavated in Conoplectus excavoides Carlton, 1983 ), ventrite VII modified into transversely oval penial plate that rotates laterally during exertion of aedeagus. Genitalia: Robust and simple, composed of basal bulb bearing sclerotized apical extensions and single median style.

Females. Similar to males in general appearance with following exceptions: eyes smaller, with fewer facets; frontal modifications absent; ventrite VII narrow, transverse (revision, Carlton 1983).

Notes. Of the seven species of North American Conoplectus included in the most recent revision ( Carlton 1983), five are found in the southeastern USA: Conoplectus acornus Carlton, 1983 ; Conoplectus bicentennialus Carlton, 1983 ; Conoplectus canaliculatus (LeConte, 1849) ; Conoplectus excavoides Carlton, 1983 ; and Conoplectus susae Carlton, 1983 . Conoplectus newtoni Carlton, 1983 is known from Guatemala, and C. tazmanuchalus Carlton, 1983 was intercepted at a US port of entry (no additional data) in material originating from Mexico. These are not discussed further. The majority of Conoplectus species have narrow distributions, with the exception of C. canaliculatus , one of the most common eastern pselaphines, which is recorded from Pennsylvania west to Texas ( Carlton 1983). Most representatives of the genus have been collected in various forest litter habitats, including forested wetlands. Conoplectus canaliculatus has been collected from rotten wood, leaf litter, sphagnum moss, and tree holes. Conoplectus susae has been found with ants in addition to forest litter ( Chandler 1990). Members of this genus and several others in the southeastern USA occur in disturbed habitats and show no preference for old-growth or mature forested habitats, in contrast to some other southeastern euplectite genera such as Pseudactium .

Based on additional specimens that have become available for study and the morphological similarity of the male genitalia, C. canaliculatus and C. acornus are synonymized (new synonomy). Conoplectus acornus was originally distinguished from C. canaliculatus based on a combination of male secondary sexual characters in the frontal region and the form of ventrite VI, despite the noted aedeagal similarity ( Carlton 1983). The aedeagus of C. acornus is similar to that of C. canaliculatus in possession of an acute, sinuate median style curved to the right, and the left and right portions of the basal bulb are separate but overlapping and sclerotized. Carlton (1983) mentioned the problematic issue of the almost identical form of the genitalia, yet pointed to the apparent absence of intermediate forms in the sympatric portion of their distributions as the reason for considering the two to be distinct species. Conoplectus canaliculatus males possess a straight, transverse frontal sulcus with a posterodorsally directed medial “horn” anterior to the sulcus, while the males of C. acornus possess an evenly rounded frontal region anterior to the sulcus lacking a horn. Intermediate forms from North Carolina possess a small horn. Other specimens within the species’ distribution feature a small notch that is visible only laterally. Thus, no reliable differences distinguish males of C. acornus from males of C. canaliculatus possessing a reduced frontal horn.

Based on a series of specimens from Little Rock, Arkansas, we make note of variation in the genitalia of C. susae ( Fig. 15 ). Members of this population possess genitalia that are similar to the typical form for the species, but possess a median lobe that is more narrowed at the apex, and the left and right processes are slightly more elaborate and sclerotized. While this population possibly represents a transitional form, differences are not pronounced enough to warrant description as a new species, and the population is mentioned here as a local variant of C. susae .

KEY TO MALES OF THE SOUTHEASTERN NORTH AMERICAN SPECIES OF CONOPLECTUS BRENDEL (Modified from Carlton 1983)

1. Frontal horn present, well-developed..........2

1′. Frontal horn absent......................................3

2. Posterior margin of transverse frontal sulcus with vertex conically produced into a vertical declivity; 3 discal elytral foveae present; Florida ....................... C. excavoides Carlton

2′. Posterior margin of transverse frontal sulcus low, evenly rounded (but see discussion above for occasional exceptions); 2 discal elytral foveae present; eastern US................. C. canaliculatus (LeConte)

3. Median style of aedeagus straight at apex, without dense patch of radiating spines on right extension of basal bulb.......................... ........................................... C. susae Carlton

3′. Median style of aedeagus hooked at apex, with dense patch of radiating spines on right extension of basal bulb .................................. ............................. C. bicentennialis Carlton

CHECKLIST OF THE SOUTHEASTERN NORTH AMERICAN SPECIES OF CONOPLECTUS BRENDEL (Modified from Chandler 1997)

Conoplectus Brendel 1888a: 301 (same paper published twice by Brendel 1888a, 1888b. 1888a has priority since it was published in June 1888, whereas 1888b paper was published in November).

TYPE SPECIES: Euplectus canaliculatus LeConte, 1849 (monotypic) .

Prorhexius Raffray 1890a: 103 , 107 (redescription as genus); Brendel 1892 (synonymy of Prorhexius with Conoplectus ).

TYPE SPECIES: Prorhexius sylvaticus Raffray (subsequent monotypy Raffray 1890b: 197) .

Hexirhexius Grigarick and Schuster 1980: 20 (as genus); Carlton 1983: 57 (synonymy of Hexirhexius with Conoplectus ).

TYPE SPECIES: Conoplectus canaliculatus (LeConte, 1849) .

REDESCRIPTION and KEY: Carlton 1983: 55–80.

Conoplectus bicentennialis Carlton, 1983 .

Conoplectus bicentennialis Carlton 1983: 73 , figs. 33–38.

TYPE DEPOSITORY: FMNH .

DISTRIBUTION: FL: Franklin Co.; FL, GA.

HABITAT: Leaf litter (sand pine, oak, palmetto); rotten tree root.

Conoplectus canaliculatus (LeConte, 1849) .

Euplectus canaliculatus LeConte 1849: 107 .

TYPE DEPOSITORY: MCZC .

Conoplectus canaliculatus Brendel 1888a: 301 (redescription in genus Conoplectus , monotypy).

Rhexidius canaliculatus Brendel and Wickham 1890: 42 (synonymy of Conoplectus with Rhexidius ); Casey 1893: 449 (subsequent redescription of Euplectus canaliculatus LeConte as Rhexidius ).

Prorhexius sylvaticus Raffray 1890a: 197 (redescription of C. canaliculatus as Prorhexius sylvaticus ); Casey 1894 (synonymy).

TYPE DEPOSITORY: MNHP .

Hexirhexius canaliculatus Grigarick and Schuster 1980: 20 (redescription in genus Hexirhexius , monotypy); Carlton 1983: 60–64 (synonymy of Hexirhexius with Conoplectus ).

Rhexius simplex Motschulsky 1856: 7 (incertae sedis Chandler 1990: 506); Chandler 1999: 167 (synonymy)

TYPE DEPOSITORY: ZMUM .

Conoplectus acornus Carlton 1983: 73 , figs. 33–38. New synonymy.

TYPE DEPOSITORY: FMNH .

DISTRIBUTION: FL: Marion Co.; GA: Clark Co.; SC: Richland Co.; AL, AR, CT, DE, FL, GA, IA, IL, IN, KY, LA, MA, MD, MI, MO, MS, NC, NH, NJ, NY, OH, OK, PA, RI, SC, TN, TX, VA, WI, WV.

HABITAT: Leaf litter (deciduous and coniferous, palmetto), rotten woods, sphagnum moss.

Conoplectus excavoides Carlton, 1983 .

Conoplectus excavoides Carlton 1983: 68–69 , figs. 19–24, 38.

TYPE DEPOSITORY: FMNH .

DISTRIBUTION: FL: Gadsden Co.

HABITAT: Leaf litter (beech).

Conoplectus susae Carlton, 1983 .

Conoplectus susae Carlton 1983: 72–73 , figs. 28–32.

TYPE DEPOSITORY: FMNH .

DISTRIBUTION: AR: Marion Co., AR, OK.

HABITAT: Leaf and log litters, collected with ants ( Chandler 1990).

Figures

Figs. 13–15. 13) Rhexius amyae - a) Habitus, dorsal view, b) Habitus, lateral view, c) Aedeagus, dorsal view;