Stenus-

Puthz, Volker, 2016, Übersicht über die neotropischen Arten der Gattung Stenus LATREILLE mit seitlich gerandetem Abdomen und ungelappten Tarsen (Coleoptera, Staphylinidae) 350. Beitrag zur Kenntnis der Steninen, Linzer biologische Beiträge 48 (2), pp. 1551-1634 : 1553-1554

Key to the neotropic Stenus- species with laterally margined abdomen and simple tarsi

1 Base of abdominal tergites simple.......................................................................................2

- Base of abdominal tergites carinate.....................................................................................3

2 Smaller, apterous species of unknown relationship (fig. 1). FB: 1.1mm. ♂: Tibiae simple, median lobe with a distinct expulsion clasp (fig. 2). ♀: No sclerotized spermatheca present. 1.8.0-2.5mm. Brazil: Alagoas ......................... S. schubarti L. BENICK - Larger, apterous or brachypterous species. FB; 1.4-1.9mm. ♂: Tibiae with or without apical/preapical spines, median lobe with a strongly sclerotized expulsion mechanism. ♀: Spermatheca distinctly sclerotized. In the high mountains of Mexico; Guatemala; Honduras; El Salvador..........................................(" Hemistenus ") popocatepetlensis -group - Larger species, mostly macropterous (5 exceptions). FB>1.8mm. Meso- and metatibae with a pre/apical tooth, median lobe without a strongly sclerotized expulsion mechanism. ♀: No distinctly sclerotized spermatheca present ............................................. .................................................................................... S. metallicus -group see separate key

3 Base of abdominal tergites with 3 carinae ...........................................................................4

- Base of abdominal tergites with 4 carinae ..........................................................................6

4 Sternum 9 serrate apicolaterally (fig. 4). ♂: Meso- and metatibiae simple, median lobe without a strongly sclerotized expulsion mechanism (fig. 7) S. megelytratus -group: 4.0- 5.0mm (FB 2.2-2.5mm). Figs 65, 71. Colombia, Ecuador................ S. megelytratus PUTHZ

- Sternum 9 acute apicolaterally. ♂: Meso- and metatibiae with or without pre/apical spines...................................................................................................................................5

5 ♂: Mesotibiae without an apical spine. E: Median lobe without strongly sclerotized expulsion mechanisms, parameres with 1-3 apical setae....................................................... ...................................................................... S. agilis- group p.p. Many neotropical species

- ♂: Mesotibiae with an apical spine. E: Medi an lobe with strongly sclerotized expulsion mechanisms, parameres (mostly) with numerous apical setae .................... S. hostilis -group see key in PUTHZ 2014: 1676 ff.

6 Pronotum with a narrow median furrow. ♀ with a distinctly sclerotized spermatheca .......7

- Pronotum without a median furrow. ♀ without a distinctly sclerotized spermatheca.. .....10

7 Punctures of elytra distinctly defined..................................................................................8

- Punctures of elytra often confluent......................................................................................9

8 Punctures of pronotum near longitudinal furrow mostly round. Abdominal punctation less dense, middle of tergites broadly impunctate. ♂: E (fig. 13). 2.9-4.0mm (FB 1.7- 1.9mm). U.S.A.; Cuba; Jamaica; Mexico............................................. S. milleporus CASEY

- Punctures of pronotum near longitudinal furrow transversely confluent. Abdominal punctation denser, middle of tergites narrowly impunctate. ♂: E (fig. 14). Mexico; U.S.A.: Arizona ......................................................................................... S. idoneus SHARP

9 Abdominal punctation fine and very dense, tergite 10 matt. ♂: E (fig. 9). 3.0-3.5mm (FB 1.8mm .............................................................................................. S. triformis PUTHZ .- Abdominal punctation fine and moderately sparse, interstices on tergite 10 smooth. ♂: E (fig. 10). 3.2-3.8mm (FB 1.9mm). Mexico...................................... S. tricornis PUTHZ

10 Segment 1 of maxillary palpi dark brown .........................................................................11

- Segment 1 of maxillary palpi yellowish. ♂: E (fig. 17). 3.0-4.0mm (FB 1.7-1.8mm). North and South America.................................................................... S. colonus ERICHSON

11 Extremely densely punctate, matt, pubescence golden, interstices of tergites reticulate. ♂: E (fig. 15). 3.0-4.0mm (FB 1.8-1.9 mm). U.S.A.: Arizona; Mexico................................ .............................................................................................................. S. egenoides PUTHZ

- Less densely punctate, pubescence whitish, interstices of tergites smooth. ♂: E fig. 16). 3.0-4.5mm (FB 1.8-1.9mm). U.S.A.; Mexico.............................................. S. stygicus SAY