Phlaeopterus cavicollis ( Fauvel, 1878 )

Mullen, Logan J., Campbell, J. M. & Sikes, Derek S., 2018, Taxonomic Revision of the Rove Beetle Genus Phlaeopterus Motschulsky, 1853 (Coleoptera: Staphylinidae: Omaliinae: Anthophagini), The Coleopterists Bulletin 72, pp. 1-54 : 16-20

3. Phlaeopterus cavicollis ( Fauvel, 1878)

( Figs. 1C , 7A , 16C, 22B–D)

Tilea cavicollis Fauvel 1878: 246 [original description]. Casey 1885: 320, 1893: 402.

Phloeopterus [sic] longipalpus Casey 1885: 318 [original description]. LeConte 1866: 375 [misidentification as P. fusconiger ]; Casey 1893: 402. New synonymy.

Tilea brevipennis Casey 1893: 404 [original description]. Hatch 1957: 60. New synonymy.

Phlaeopterus cavicollis ( Fauvel, 1878) : Bernhauer and Schubert 1910: 74; Hatch 1957: 60; Moore and Legner 1979: 208; Gandhi et al. 2001: 139; Hilchie 2007: 12; Bousquet et al. 2013: 89; Shavrin and Mullen 2015: 121.

Type Locality. British Columbia, Canada .

Redescription. Habitus: Length 6.3–9.2 mm. Brown to reddish brown; elytra and lateral and basal margins of pronotum often lighter; palpi and epipleura sometimes lighter ( Fig. 1C ). Head: Broad, ratio of width across eyes to length of head about 5:4. Interantennal groove broadly and deeply impressed. Anteocellar foveae large, deeply impressed. Eyes glabrous or with less than 10 scattered setae near ventral margin. Antennomeres 5–10 at least 2 times longer than wide; antennomeres 4–11 each with many sensory pits with papilliform projections. Ocelli present. Nuchal constriction vague. Mandibular molar area with L-shaped row of setae. Labrum with sensory pores along entire surface. Labial palpi with 3 rd palpomere 1.6–1.8 times longer than palpomere 2. Thorax: Pronotum wide (Fig. 16C), length to width ratio = 0.61–0.68; ratio of pronotal width to head width = 1.49–1.72; maximum width subequal to elytral width at humeral angle; punctures on dorsal surface separated by average distance equal to approximately twice as great as diameter of a puncture; lateral margins broadly explanate anterad and posterad lateral foveae; lateral foveae deeply impressed. Elytra with humeral angles convex; epipleural carina not projecting; 2.2–2.7 times longer than pronotum; apical margins broadly convex to nearly truncate. Wings fully developed in most individuals, brachypterous in very few. Mesosternum with projecting tooth, tooth more strongly notched on posterior margin than on anterior margin; longitudinal carina along midline of mesosternum complete. Legs: All tibiae with dense pubescence to apex or with small subglabrous region at apex. Metatrochanter without tooth on apical margin. Abdomen: Wing-folding spicules on tergites IV and V broad, transverse, narrowly separated; tergite VI lacking wing-folding spicules. Aedeagus: Somewhat variable ( Fig. 22B–D ), 1.28–1.72 mm long. Median lobe convexly converging from base to midline, gradually converging from midline to apex. Parameres diverging from base to near apex, then converging towards apex of median lobe. Internal sac elongate, rectangular to narrowest near midline, subapical transverse fold present or absent.

Type Specimens. Tilea cavicollis : Lectotype male (here designated, UAMObs:Ento:235220) and paralectotype female (here designated, UAMObs:Ento:232466) labeled as follows: Columbie britannique/ Syntype / LECTOTYPE ³ (or PARALECTOTYPE ♀) Tilea cavicollis Fvl. , desig. 1984 J.M. Campbell/ Phlaeopterus cavicollis (Fvl.) , det. 1984, J.M. Campbell. The paralectotype female is missing Fauvel’ s handwritten determination label but otherwise has identical label data. We designated these specimens as lectotype and paralectotype to clarify the application of this name to this taxon and because a holotype was not designated in the series examined by Fauvel (1878), which comprised an unknown number of specimens. Both specimens are in the RBINS.

Phloeopterus [sic] longipalpus : Lectotype male (here designated to clarify the application of this name to this taxon, UAMObs:Ento:235764) labeled as follows: Oct.3/Placer Co. CAL./ ³/ T. longipalpus Cas. /CASEY bequest 1925/TYPE USNM 48106/ Lectotype ³ Phlaeopterus longipalpus Casey des. 1984, J.M. Campbell. We designated this specimen as a lectotype because a holotype was not designated in the series examined by Casey (1885). The Casey Collection contains seven other specimens collected from “Placer Co., Cal.” with a label stating “#2 and #7 may be paratypes ”. However, Casey (1885) examined at least one female, and these two specimens are males, so we could not determine which two of the seven specimens should be paralectotypes. The lectotype is in the USNM.

Tilea brevipennis : Holotype male (UAMObs: Ento:235786) labeled as follows: Wy/³/CASEY bequest 1925/TYPE USNM 48109/brevipennis/ HOLOTYPE ³ Phlaeopterus brevipennis Casey. This specimen is in the USNM.

Distribution. Phlaeopterus cavicollis is widely distributed in western North America from southern California north through the Pacific Coast and Cascade Ranges and the Rocky Mountains of British Columbia to southeastern Alaska, and east to Wyoming and Colorado ( Fig. 7A ). Adults have been collected during June–October, and in November in California, at 600–3,500 m elevation.

Bionomics. Adults have been observed feeding on wind-blown insects (mostly Diptera) on the surface of snowfields, breeding on the surface of snowfields, and rarely flying. Adults have also been collected under rocks at the edges of snowfields and in moss or under rocks at the edges of cold, fast streams or springs at lower elevations.

Remarks. Phlaeopterus cavicollis can be distinguished from all other Phlaeopterus species except for P. bakerensis by having lateral margins of the pronotum broadly and subequally explanate anterad and posterad the lateral foveae. Phlaeopterus cavicollis can be distinguished from P. bakerensis by its smaller size and lacking projecting humeral angles of the elytra. We chose to synonymize P. brevipennis and P. longipalpus under P. cavicollis due to their shared characters (see Redescription) and the presence of intermediate forms.

The morphological variation that has previously been used to differentiate these three species is as follows. Specimens of P. longipalpus from the Sierra Nevada Mountains, the Trinity Alps, and Mt. Lassen, California have the tibiae evenly pubescent to the apex and the internal sac of the aedeagus roughly rectangular with a subapical transverse fold ( Fig. 22D ). Specimens of P. cavicollis from Alaska, British Columbia, and the Pacific Coast and Cascade Ranges south to northern California usually also have the tibiae evenly pubescent to the apex and the internal sac of the aedeagus roughly triangular but lack a subapical transverse fold ( Fig. 22B ). Most specimens ( P. brevipennis ) from the Rocky Mountains, Washington, Montana, and Colorado have the apex of the tibiae narrowly glabrous (but a few have pubescence evenly distributed to the apex) and the internal sac of the aedeagus without a subapical transverse fold ( Fig. 22C ) and with margins narrowed near the midline. Some specimens intermediate between P. cavicollis and P. brevipennis from eastern Oregon, eastern Washington, and Idaho cannot be assigned to either name with certainty.

It is difficult to be certain whether these populations should be regarded as a single, broadly distributed, variable species or three distinct species. Given the available morphological evidence, we chose to regard them as a single species. Genetic analysis would be useful in testing these synonymizations, but at present no sequence data are available for this species.

Figures

Fig. 1. Phlaeopterus species, habitus. A) P. bakerensis, female (UAMObs:Ento:233271), B) P. castaneus, female

Fig. 7. Distributions of Phlaeopterus species based on all georeferenced specimen records. A) P. cavicollis, B) P. czerskyi. Grey dots represent localities where at least one Phlaeopterus species, but not the species of interest, was collected. Red dots represent localities where the species of interest was collected.

Fig. 22. Phlaeopterus species, aedeagi (left = ventral view; right = dorsal view of median lobe). A) P. castaneus castaneus, B–D) variation in P. cavicollis.