Oedichirus isthmus, Herman, 2013

Herman, Lee H., 2013, Revision Of The New World Species Of Oedichirus (Coleoptera: Staphylinidae: Paederinae: Pinophilini: Procirrina), Bulletin of the American Museum of Natural History 2013 (375), pp. 1-137 : 92-94

Oedichirus isthmus , new species

Figures 39 , 160–165

HOLOTYPE: Male. ‘‘Mex: Est. Biol. Chamela, Jalisco VII-20/27-1984 J.T. Doyen coll./ Oedichirus 1st Mex. record M.K. Thayer det. 1999 / Holotype Oedichirus isthmus Herman. ’’ Deposited in the Essig Museum of Entomology , University of California , Berkeley, California .

TYPE LOCALITY: Mexico: Jalisco: Estación Biologica de Chamela (19 ° 229–399N, 104 ° 569– 105 ° 109W). (Coordinates for the station are from a website of the Smithsonian Institution [http://botany.si.edu/projects/cpd/ma/ma7.htm].)

DIAGNOSIS: Oedichirus isthmus is one of six New World species with paratergite III. Of these six, O. hamatus , known only by the female, has dark femorotibial maculations (as in fig. 2); O. isthmus lacks the spots. Among the remaining species only O. isthmus and O. sinuosus have short parameres (figs. 161, 200); the parameres of O. batillus , O. bicristatus , and O. optatus are long (figs. 49, 57, 189 respectively). The emargination of sternum VIII of both O. isthmus and O. sinuosus is broad; sternum VIII of the former has a transverse, subapical cluster of setae (fig. 163), the latter has a curved, transverse, subapical row of setae (fig. 203). The apical region of the median lobe of O. isthmus is broader (fig. 161) than it is for O. sinuosus (fig. 200). Sternum VIII of O. bicristatus has a deep, symmetrical emargination, a large, dense, median patch of spiniform setae, and the transverse basal ridge is strongly curved medially (fig. 59); for O. isthmus the asymmetrical emargination of sternum VIII is shallower, the cluster of setae of sternum VIII is smaller, and the transverse basal ridge of the sternum is sinuate and not strongly curved medially (fig. 163). In contrast to O. isthmus (fig. 163), sternum VIII of O. batillus lacks spinelike setae and has a wide deep emargination (fig. 53). Many features of O. optatus , including the deep, narrow emargination of sternum VIII (fig. 193), the form of the aedeagus (figs. 188, 189), and the presence of six labral denticles separate it from O. isthmus . The female of O. isthmus is unknown.

DESCRIPTION: Length 7.3 mm. Width 1.1 mm. Length of head: 0.8 mm. Width of head: 1.0 mm. Pronotal length: 1.2 mm. Pronotal width: 1.0 mm. Elytral length: 1.0 mm. Elytral width: 1.1 mm.

Body concolorous reddish brown. Legs concolorous yellowish brown; femorotibial joints without dark spots.

Head about one third wider than long (HW/HL: 1.3). Frontoclypeal ridge incomplete, separated medially. Dorsal surface without V-shaped depression; surface polished and sparsely punctate medially from anterior to posterior regions; lateral surface with shallow, moderately coarse, and moderately dense punctation from just before eye to near basal margin. Labrum quadridentate; surface without tubercle near submedial denticle.

Pronotum about one fifth longer than wide (PL/PW: 1.2). Pronotum polished, with coarse, dense punctation, and with moderately large impunctate spots; punctures clustered in large lateral group and in long, submedial group; surface without distinct submedial, punctate groove. Elytra with width about one tenth greater than length (EW/EL: 1.1); surface flat medially and coarsely punctate.

Abdominal terga V to VII with subapical row of punctures; punctation of terga III to V with irregularly arranged, poorly developed subapical transverse row of punctures; terga VI and VII with moderately developed, subbasal, subapical, and apical, transverse rows of punctures, subbasal and subapical rows with punctures irregularly arranged; VII and VIII with finer punctation than on preceding segments. Segment III with narrow paratergite; paratergal carina absent. Tergum III without median point extending from transverse basal ridge. Tergum VIII with broad, shallow emargination of posterior margin; transverse basal ridge broadly and shallowly curved anteriorly, not separated medially, and without median point. Tergum IX with lateroapical process about one third longer than midbasal length (LLaP/L9 5 1.3), moderately bent ventrally, and approximately parallel to other process; ventromedial margin without posteriorly directed spur (cf. fig. 158).

MALE: Sternum VI unmodified. Sternum VII (fig. 165) with large, median cluster of short, semirecumbent, spiniform setae near posterior margin. Sternum VIII (fig. 163) with wide, moderately asymmetrical, moderately deep emargination of posterior margin; emargination about one twelfth of median length of sternum, wider than deep, mostly to right of midlongitudinal line, and margin broadly rounded basally and membranous; surface with transverse, subapical cluster of spiniform setae near middle adjacent to posterior margin, without carinae, combs, or depressions, and with broad, moderately deep, sparsely punctate, polished, transverse depression between submarginal cluster of setae and transverse basal ridge; transverse basal ridge slightly sinuate and without posteriorly directed median point. Tergum IX with long, moderately wide process on anterior margin of anteroventral angle. Sternum IX (fig. 164) moderately asymmetrical; anterior margin narrow and broadly round- ed; posterior margin wide and broadly rounded; lateral margins sinuate.

Aedeagus asymmetrical (figs. 160–162). Median lobe constricted subapically (fig. 161) and with swollen apical bulb (fig. 160); apical margin broadly rounded; ventral surface with curved carina extending anteriorly from apical bulb for about one third of length of medial lobe; ventral sclerite without apicoventral process extending from posterior margin. Parameres short, fused to median lobe basally, and free apically; parameres of approximately equal length. Internal sac with long, cylindrical, apically open flagellum (figs. 160, 161).

FEMALE: Unknown.

ETYMOLOGY: The name is from the Greek isthmos,:neck or narrow passage’’ and refers to the subapical constriction of the median lobe of the aedeagus.

DISTRIBUTION: Known only from the west central Mexican state of Jalisco (fig. 39).

REMARKS: This species, represented by one male, is one of two known for Mexico.

Figures

Figs. 39–40. Oedichirus species. Distribution. 39. Mesoamerica and the Caribbean. 40. South America. (Species described prior to present work preceded with *. Symbols ³ or ♀ signify species known only by the sex indicated. Open circle denotes multiple collecting sites.)

Figs. 160–164. Oedichirus isthmus. 160. Aedeagus, right lateral. 161. Aedeagus, ventral. 162. Aedeagus, left lateral. 163. Sternum VIII, male. 164. Sternum IX, male.

Fig. 165. Oedichirus isthmus. Sternum VII, male (CLSM).