Osoriinae Erichson 1839
Creators: name: Pandolfi, Alessandra
name: Kelly, Sandor
name: Irmler, Ulrich
name: Bohlen, Patrick
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae

description: Key to Osoriinae of the Southeastern USA
A key to genera and species is provided and is adapted from Newton et al. 2000 (genera), Irmler 2003 (Clavilispinus), Notman 1925 and Irmler 2014 (Osorius and Molosoma), Chapin 1928 (Holotrochus and Mimogonus), Ferro 2015 (Thoracophorus), and Newton 2017 (Clavilispinus and Prolibia).
1 Membranous suture present between each abdominal tergum and sternum; pronotum gradually but strongly narrowed toward base for basal 1/3 or more (triangle-like shape); body very flat................................................. 2
- Abdominal tergum and sternum of each of segments III–VII fused into complete ring; pronotal shape diverse, rarely gradually and strongly narrowed toward base (trapezoid-like shape); body flat to convex or cylindrical......................... 3
2 Head without groove near dorsal edge of eye; pronotum longer than wide (rarely only as long as wide), with sides subparallel for the anterior 2/3; elytron with sutural stria................................... Renardia nigrella (LeConte, 1863)
- Head with groove extending posteriorly from dorsal edge of eye; prontum distinctly wider than long, with sides subparallel for at most the anterior 1/2; elytron without sutural stria................................ Eleusis pallida (LeConte, 1863)
3 Procoxa with deep groove and carina on mesal surface; protibia with inner edge concave and bearing ctenidium; abdominal segment VIII (last visible) with “extra” tergite at apex; body convex, often nearly cylindrical......................... 4
- Procoxa with or without carina on mesal surface; protibia with inner edge straight, without ctenidium; abdominal segment VIII without “extra” tergite at apex (but part of eversible genital segment may be visible); body generally more or less flat.... 11
4 Antenna geniculate; scape about as long as or longer than next three antennomeres combined; external edge of protibia strongly convex, strongly spinose............................................................................... 5
- Antennae not geniculate; scape about as long as next 2 antennomeres combined; external edge of protibia straight to slightly convex, at most with a few slender spines................................................................. 9
5 Length 6 mm or greater................................................................................ 6
- Length 5.5 mm or less................................................................................. 8
6 Clypeus strongly emarginate.................................................... Osorius politus LeConte, 1877
- Clypeus truncate or subtruncate......................................................................... 7
7 Head distinctly narrower than the pronotum; pronotum and elytra shiny and densely punctured; length 6 mm ...................................................................................... Osorius parviceps Notman, 1925
- Head not narrower than the pronotum; pronotum and elytra dull and not densely punctured; length 7–8 mm ...................................................................................... Osorius planifrons LeConte, 1877
8 Second antennal segment subequal in length to third, following segments approximately quadrate; thoracic and elytral punctures in general coarser and more numerous; length 5–5.5 mm ....................... Molosoma latipes (Gravenhorst, 1806)
- Second antennal segment distinctly longer than third, following segments transverse; thoracic and elytral punctures in general sparser and finer; length 3.5–4 mm ........................................ Molosoma brevicorne (Notman, 1920)
9 Pronotum in front of posterior edge deeply emarginate, posterior angles with depression; pronotum and elytra pubescent; body reddish-brown, elytra slightly lighter reddish; introduced in Florida ................ Mimogonus fumator (Fauvel, 1889)
- Pronotum in front of posterior edge not emarginate, posterior angles without depression; pronotum and elytra glabrous; body dark brown, elytra same color of the rest of the body........................................................ 10
10 Length of pronotum greater than length of elytral suture, sides explanate; elytra rugose-punctate; body relatively robust, length 2.7 mm ............................................................. Holotrochus brachypterus Fauvel, 1905
- Length of pronotum equal to length of elytral suture, sides narrow, not explanate; elytra simply punctate; body relatively slender, length 2.5 mm ................................................... Holotrochus parvulus Chapin, 1928
11 Procoxae separated ventrally by a flat or convex process of prosternum......................................... 12
- Procoxae contiguous................................................................................. 13
12 Abdominal segments with coarse diagonal to nearly longitudinal strigae, at least ventrally... Lispinus obscurus LeConte, 1863
- Abdominal segments without coarse strigae...................................... Nacaeus tenuis (LeConte, 1863)
13 Procoxal fissure open, trochantin exposed................................................................ 14
- Procoxal fissure closed, trochantin concealed.............................................................. 16
14 Head (including eyes) about 2/3 as wide as combined elytral width; pronotum widest in middle third; pronotosternal suture solid, present as a fine external carina; abdominal tergum VIII (last visible) entire, separated laterally from sternum VIII by suture................................................................. Prolibia laevicauda (LeConte, 1866)
- Head (including eyes) more than 4/5 as wide as combined elytral width; pronotum widest in anterior third; pronotosternal suture absent; abdominal sternum VIII extended dorsally in front of tergum VIII and fused to it near midline................. 15
15 Red; dorsal microsculpture deep and distinct, microsculpture on abdomen as deep and distinct as that of elytra; length greater than 2.5 mm ......................................................... Clavilispinus rufescens (LeConte, 1863)
- Yellow; dorsal microsculpture relatively less deep and distinct, microsculpture on abdomen not as deep and distinct as that of elytra; length 1.9–2.1 mm ............................................... Clavilispinus exiguus (Erichson, 1840)
16 Elytra (sometimes also head or pronotum) costate; body surfaces generally roughly sculptured and microsculptured, dull; abdominal sternum VIII extended dorsally in front of tergum VIII............................................. 17
- Elytra not costate; body coarsely punctate or not, with or without depressions along midline of pronotum but otherwise without rough sculpture, more or less shining; abdominal sternum VIII normal, not visible from above.................................................................................... Espeson Schaufuss, L. W., 1882 (undescribed sp.)
17 Eyes visible from above; combined length of pronotum and elytra <0.7 mm; pronotal disc with 2 sublateral ridges; restricted in the US to Florida ................................................ Thoracophorus guadalupensis Cameron, 1913
- Eyes not visible from above; combined length of pronotum and elytra> 0.8 mm; pronotal disc with 2 apically bifurcated, sublateral ridges, or pronotal disc with 4 ridges; widespread.................................................. 18
18 Pronotal disc with 2 apically bifurcated, longitudinal ridges; vertex of head with 2 irregular carinae..................................................................................... Thoracophorus brevicristatus (Horn, 1871)
- Pronotal disc with 4 longitudinal ridges; vertex of head with 4 complete carinae.... Thoracophorus costalis (Erichson, 1840)
description: Published as part of Pandolfi, Alessandra, Kelly, Sandor, Irmler, Ulrich & Bohlen, Patrick, 2024, First record of Mimogonus fumator (Fauvel, 1889) (Coleoptera: Staphylinidae: Osoriinae) in the USA, with a synopsis of the Osoriinae of the Southeastern USA, pp. 136-146 in Zootaxa 5477 (2) on pages 142-143, DOI: 10.11646/zootaxa.5477.2.2, http://zenodo.org/record/12683406