Stenus aenescens LYNCH ARRIBALZAGA

Puthz, V., 2014, Neue und alte neotropische Stenus-Arten (Coleoptera, Staphylinidae) 339. Beitrag zur Kenntnis der Steninen, Linzer biologische Beiträge 46 (2), pp. 1671-1736 : 1720-1721

Key to the species of the group of Stenus aenescens LYNCH ARRIBALZAGA

(DN = depth of apical emargination of sternite 8; LS = length of sternite)

1 Forebody densely reticulate.: Unknown. 4.0-4.2mm (FB 2.0-2.1mm). Argentina........... .......................................................................................................... S. aeneomicans PUTHZ

- Forebody without reticulation.............................................................................................2

2 Frons concave with or without a slightly elevated median portion, median portion (mostly) below the level of medial eye margins.................................................................3

- Frons not concave, elevated median portion extending about to or over the level of medial eye margins...........................................................................................................16

3 Head broader than elytra or nearly as broad as (HW: EW 0.95).......................................4

- Head less broad (HW: EW 0,95).....................................................................................11

4 Median portion on frons complete flat................................................................................5

- Median portion of frons slightly elevated...........................................................................7

5 Interstices of tergite 7 reticulate. 4.5-5.6mm (FB 2.4-2.6mm).: E (fig. 163). Brazil........ ................................................................................................................. S. teres ERICHSON

- Interstices of tergite 7 smooth.............................................................................................6

6 Head distinctly broader than elytra (HW: EW 1.05). Larger: 4.5-5.0mm (FB 2.3- 2.4mm).: E (fig. 165). Bolivia.......................................................... S. rufipes L. BENICK

- Head slightly less broad (HW: EW 0.95). Smaller: 4.0-5.0mm (FB 2.2mm).: E (fig. 164). Brazil........................................................................................... S. riguus L. BENICK

7 Head distinctly broader than elytra, abdomen distinctly reticulate.....................................8

- Head distinctly less broad than elytra (HW: EW 0.94), abdomen without reticulation. 4.3-4.7mm (FB 2.1-1.3mm).: E fig. 167). Brazil............................. S. sodalis L. BENICK

8 Tergite 10 spadous, posteriorly pointed (figs 148, 150)......................................................9

- Tergite ± 10 rounded at posterior margin. 4.2-5.3mm (FB 2.2-2.4mm). Brazil.................... .................................................................................................... S. curtipennis BERNHAUER

9 Sternum 9 with a short apicolateral tooth (fig. 156)..........................................................10

- Sternum 9 with a longer, acute apicolateral tooth (fig. 149). Brazil. see #8.......................... .................................................................................................... S. curtipennis BERNHAUER

10: E (fig. 166), median lobe acute apically. 3.9-4.7mm (FB 2.1-2.2mm). Brazil................ ........................................................................................................... S. mantiqueira PUTHZ

-: E (fig. 162). median lobe split apically. 4.0-4.8mm (FB 2.1mm). Brazil........................ ........................................................................................................ S. artipennis L. BENICK

11 Tergite 8 reticulate............................................................................................................12

- Tergite 8 not reticulate. 4.0-4.7mm (FB 2.1-2.2mm).: Segment 1 of metatarsi much broader than segment 2, metatibiae compressed medially. Apical notch of sternite 8 deeper (LS: DN=1.9), E (about as in fig. 111, but median lobe longer than parameres). Brazil......................................................................................................... S. cerritus SHARP

12 Head broader, HW: EW 0.96. Abdomen shallowly reticulate. 3.6mm (FB 1.8mm).: E (figs. 106, 114). Bolivia.................................................................... S. holmgreni nov.sp.

- Head less broad, HW: EW 0.90. Anterior tergites not reticulate....................................13

13 Tergite 10 slightly concave at apical margin (fig. x).: Metafemur (fig. 131). E (fig. 95). 3.8-4.8mm (FB 2.2-2.3mm). Bolivia........................................... S. femoridens nov.sp.

- Tergite 10 otherwise..........................................................................................................14

14 Tergite 10 evenly rounded at posterior margin (fig. 125).: Metafemur simple. E (fig. 168). 3.6-4.3mm (FB 1.9-2.0mm). Bolivia..................................... S. corticivagans nov.sp.

- Tergite 10 very shallowly emarginate at posterior margin................................................15

15 Tergite 7 with faint, tergite 8 with distinct reticulation.: E (fig. 112). 3.2-4.1mm (FB 1.9-2.0mm). Peru.............................................................................................. S. inti PUTHZ - Tergites 7 and 8 without reticulation. 3.2-3.8mm (FB 1.8-1.9mm).: Segment 1 of metatarsi simple as are the metatibiae. Apical notch of sternite 8 less deep (SL: DN= 2.4). E (fig. x). Peru............................................................................... S. cerritulus PUTHZ

16 Tergite 10 with an acute median tip (figs 136, 140, 142)..................................................17

- Tergite 10 otherwise..........................................................................................................20

17 Apicomedian tip of tergite 10 minute (fig. 136, 142)........................................................18

- Apical tip of tergite 10 longer (fig. 140)...........................................................................19

18 Tergite 7 densely reticulate, anterior tergites shallowly reticulate.: Unknown. Argentina..................................................................................... S. argentinus BERNHAUER

- Tergite 7 not reticulate (at most with traces of reticulation posteriorly).: E (fig. 115). 4.0-4.6mm (FB 2.1-2.2mm). Argentina................................................... S. spicatus nov.sp.

19 Larger, head slightly broader than elytra (HW: WÉ =1.01).: Unknown. 4.5-4.8mm (FB 2.2-2.3mm). Paraguay....................................................... S. paraguyanus BERNHAUER

- Smaller, 3.7-4.3mm. Head slightly narrower than elytra (HW: EW <0.97)......................19

20 Tergite 10 (fig. 113). Shoulders rectangular.: E (fig. 136). 3.9-4.3mm (FB 1.7- 1.8mm). Brazil, Paraguay, Argentina............................................ S. plaumannianus PUTHZ

- Tergite 10 (fig. 142). Shoulders slightly oblique.: E (fig. 169). 3.7-4.3mm (FB 2.0- 2.1mm)............................................................................................ S. spinuliventris nov.sp.

21 Tergite 10 distinctly concave at posterior margin (figs 118, 119, 133, 134).....................22

- Tergite 10 not or shallowly concave at posterior margin (figs 143, 144)..........................25

22 Head distinctly narrower than elytra (HW: EW 1.15). Tergite 10 (figs 118, 119).: E (fig. 157): 3.7-4.2mm (FB 2.2.1mm). Argentina, Paraguay, Bolivia, Uruguay.................... ...................................................................................... S. aenescens LYNCH ARRIBALZÁGA

- Head less narrower than elytra (HW: EW <1.13).............................................................23

23 Abdomen completely, distinctly reticulate.: Sternite 9 (fig. 145), E (fig. 159). 4.0- 4.7mm) FB 2.3-2.4mm). Peru, Bolivia........................................ S. titicacanus BERNHAUER

- Anterior tergites not (or very shallowly) indistinctly reticulate........................................24

24: Apical notch of sternite 8 deeper (LS: DN  5). E (fig. 160). 3.8-4.8mm (FB 1.9- 2.2mm). Chile....................................................................................... S. hogansoni PUTHZ

-: Apical notch of sternite 8 less deep (LS: DN =3.9). E (fig. 158). 3.2-3.6mm (FB 2.0mm). Bolivia........................................................................... S. corticihabitans nov.sp.

25 Smaller, tergite 8 without reticulation; tergite 10 rounded at posterior margin (fig. 129).: Unknown. 3.0-3.8mm (FB 1.7-1.9mm). Argentina........... S. densepilosus nov.sp.

- Larger, tergite 8 with distinct reticulation, tergite 10 rounded or slightly emarginate at posterior margin (figs 120, 128, 138)................................................................................26

26 Tergite 10 rounded at posterior margin (fig. 120). E (fig. 168). 4.3-5.0mm (FB 2.2- 2.3mm). Argentina................................................................................ S. daguerrei nov.sp.

- Tergite 10 emarginate at posterior margin........................................................................27

27 Punctation and reticulation of tergite 8 deeper and denser (fig. 104), tergite 10 (fig. 128).: E (fig. 116). 3.8-4.2mm (FB 2.0-2.1mm). Argentina, Brazil.................................. ....................................................................................................... S. crassipes BERNHAUER

- Punctation and reticulation of tergite 8 less coarse and less deep (fig. 105),: E (fig. 138). 4.0-5.2mm (FB 2.2-2.4mm). Brazil.................................................. S. scissus PUTHZ