Micrillus RAFFRAY.
Creators: name: Assing, V.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Micrillus

description: Key to the Palaearctic and Oriental species of Micrillus and Scymbalium
For convenience, Micrillus aethiopicus, a close relative of M. aegyptiacus, is included in the key, although this species has been recorded only from the Afrotropical region.
1 Protarsomeres I-IV dilated in both sexes. Species of moderately large to large size; body length> 7.0 mm; length of forebody> 3.8 mm. Genus Scymbalium ERICHSON ........2
- Protarsomeres I-IV not dilated. Small to moderately large species; body length 3.2-9.0 mm; length of forebody 1.8-4.0 mm. Genus Micrillus RAFFRAY ........................................5
2 Head and pronotum with distinct and moderately dense punctation (Fig. 3). West Palaearctic region................................................................................................................3
- Head and pronotum with very fine (sometimes except for some scattered macropunctures on frons), sparse or very dense punctation (Figs 6, 57, 61). East Palaearctic and Oriental regions..........................................................................................4
3 Abdomen with very fine punctation (Fig. 4). Iraq, Russian South European territory.......... .......................................................................................................... S. persimile CAMERON
- Abdomen with distinctly coarser punctation. Widespread, from France and Algeria to Turkmenistan and Iran ...................................................................... S. anale (NORDMANN)
4 On average larger species of more robust habitus (Fig. 56); body length 8.5-9.5 mm; length of forebody 4.8-5.1 mm. Head with rather dense and moderately fine punctation (Fig. 57). Male sternite VIII with deeper posterior concavity (Fig. 58). Ventral process of aedeagus apically more slender and more strongly bent dorsad in lateral view (Figs 59-60). Northeastern India; Bhutan; Myanmar ......................... S. badium (MOTSCHULSKY)
- On average smaller species of more slender habitus (Figs 5-6, 63); body length 7.5-8.5 mm; length of forebody barely 3.9-4.7 mm. Head with extremely fine and sparse punctation (Fig. 61). Male sternite VIII with shallowly concave posterior margin (Figs 62, 64). Aedeagus 0.6-0.7 mm long, ventral process apically stouter and less strongly bent dorsad in lateral view (Figs 7-8, 65-66). Nepal ............................ S. nepalense nov.sp.
5 Apical joint of maxillary palpus long and slender, at least half the length of preapical palpomere (ASSING 2008: figure 39). Aedeagus of simple morphology, symmetric, usually slender with ventral process apically more or less bent dorsad; internal structures amorphous and weakly sclerotised. West Palaearctic region (including Middle Asia); absent from Egypt (ASSING 2008: figure 2). Micrillus testaceus group.......6
- Apical joint of maxillary palpus of conical shape and usually shorter than half the length of preapical palpomere, only in one species from the Oriental region longer. Aedeagus of complex morphology, usually asymmetric and/or with more or less distinctly sclerotised internal structures. Afrotropical, East Palaearctic, and Oriental regions, in the West Palaearctic confined to Egypt and Yemen. Micrillus aegyptiacus and M. suturalis groups.....................................................................................................13
6 Eyes fully developed or of reduced size, but always composed of ommatidia. Posterior margin of abdominal tergite VII at least with narrow rudiment of a palisade fringe..........7
- Eyes extremely reduced, without ommatidia. Abdominal tergite VII without palisade fringe. Distribution confined to North Africa....................................................................11
7 Posterior margin of head distinctly concave in the middle (ASSING 2008: figure 61). Eyes, elytra, and hind wings not reduced (ASSING 2008: figures 59-60, 62). Posterior margin of male sternite VIII with deeply and broadly triangular excision (ASSING 2008: figure 64). Aedeagus as in ASSING 2008: figures 66-74. Known distribution confined to Iraq, Israel, and Iran ................................................... M. irakensis (CAMERON)
- Posterior margin of head not distinctly concave, usually truncate. Aedeagus of different morphology..........................................................................................................8
8 Species of pale (yellowish, reddish or pale brown) coloration. Eyes, elytra, and hind wings not reduced (ASSING 2008: figures 48-49). Posterior margin of male sternite VIII with shallow emargination (ASSING 2008: figure 50). Aedeagus of distinctive shape, rather broad in ventral view, ventral process apically not bent dorsad, and with two clusters of moderately sclerotised internal structures (ASSING 2008: figures 51-55). Caucasus region and Middle Asia ..................................................... M. pallidus (REITTER)
- Mature specimens usually (but not always!) of darker coloration, reddish to dark brown. Eyes, elytra, and hind wings often of reduced size or length, respectively. Aedeagus more slender, with one cluster of internal structures and with ventral process apically bent dorsad............................................................................................................9
9 Wing-dimorphic, on average smaller species; eyes on average larger. Elytra and abdomen with finer punctation (ASSING 2008: figure 11). Posterior margin of male sternite VIII with deeper triangular emargination (ASSING 2008: figure 13). Widespread species with slender aedeagus with more weakly sclerotised ventral process (ASSING 2008: figures 16-26), or distribution confined to Algeria .......................10
- Monomorphic brachypterous species (ASSING 2008: figures 34-35); eyes (ASSING 2008: figure 38) usually smaller. Elytra and abdomen with coarser and denser punctation (ASSING 2008: figures 35, 37). Posterior margin of male sternite VIII with shallow emargination (ASSING 2008: figure 56). Aedeagus relatively broad and with rather strongly sclerotised ventral process (ASSING 2008: figures 41-46). Endemic to northern Morocco ............................................................................ M. scabrosus (FAUVEL)
10 Aedeagus longer (> 0.75 mm), slender, and with weakly sclerotised internal structures (ASSING 2008: figures 16-26). Widespread in the south of the West Palaearctic region (Map 1).......................................................................................... M. testaceus (ERICHSON)
- Aedeagus shorter (<0.70 mm), broader, and with distinctly sclerotised internal structures (ASSING 2008: figures 106-110). Known only from the surroundings of Biskra, Algeria ................................................................................ M. biskrensis (FAUVEL)
11 Elytra slightly narrower than pronotum (ASSING 2008: figure 98). Eye rudiments (ASSING 2008: figure 99) slightly larger, 0.06-0.07 mm. Aedeagus apically pointed in ventral view (ASSING 2008: figures 102-103). Known only from two localities in Taza district, Morocco ............................................................................. M. tenuipennis ASSING
- Elytra approximately as wide as pronotum. Eye rudiments smaller (ASSING 2008: figures 77, 88), eye length 0.03-0.05 mm. Aedeagus apically weakly to distinctly concave in ventral view. Distribution confined to Algeria ................................................12
12 Smaller species; head length <0.80 mm, head width <0.80 mm, width of pronotum <0.80 mm. Antennae shorter (ASSING 2008: figure 89), <2.05 mm long. Eye rudiments smaller (ASSING 2008: figure 88), eye length 0.03-0.05 mm. Pronotum on average more oblong (ASSING 2008: figure 87). Head approximately as broad as long (ASSING 2008: figure 87) and smaller in relation to pronotum, approximately as wide as pronotum (ASSING 2008: figure 87). Head with coarser and denser punctation and with more pronounced microsculpture (ASSING 2008: figure 87). Aedeagus apically weakly concave in ventral view and less strongly bent dorsad in lateral view (ASSING 2008: figures 93-95). Algeria: surroundings of Algier ......................... M. subterraneus RAFFRAY
- Larger species; head length 0.90 mm, head width> 0.85 mm, width of pronotum> 0.80 mm. Antennae longer (Fig. 78),> 2.15 mm long. Eye rudiments slightly larger (ASSING 2008: figure 77), 0.05 mm long. Pronotum on average less oblong (ASSING 2008: figure 76). Head oblong (ASSING 2008: figure 76), larger in relation to pronotum, and wider than pronotum (ASSING 2008: figure 76). Head with finer and sparser punctation and with weaker microsculpture (ASSING 2008: figure 76). Aedeagus apically distinctly concave in ventral view and strongly bent dorsad in lateral view (ASSING 2008: figures 81-85). Algeria: Djebel Bou Zegz ................................. ............................................................................................. M. hypogaeus (PEYERIMHOFF)
13 Species from North Africa................................................................................................14
- Species distributed in the East Palaearctic and Oriental regions.......................................17
14 Smallest species of the genus; head length <0.60 mm, head width <0.60 mm, length of pronotum <0.65 mm, width of pronotum <0.55 mm. Wing-dimorphic (ASSING 2008: figures 128-129); brachypterous morph with very small eyes (ASSING 2008: figure 130), short elytra, and reduced hind wings (ASSING 2008: figure 129). Valvulae of abdominal segment IX relatively short (ASSING 2008: figure 136). Male sternite VIII posteriorly very deeply and very narrowly incised (ASSING 2008: figures 134-135). Aedeagus of distinctive morphology (ASSING 2008: figure 130-134). Egypt and Sudan ...... .......................................................................................................... M. torretassoi (KOCH)
- Distinctly larger, monomorphic macropterous species with distinctly larger eyes. Valvulae of abdominal segment very long. Male sternite VIII posteriorly with much less deep and broader excision. Aedeagus of completely different morphology...............15
15 Abdomen with less dense and more distinct punctation and with less pronounced microsculpture. Head subparallel behind eyes. Eyes rather small and weakly convex (ASSING 2008: figures 112-113). Head oblong. Male sternite VIII without modified setae and with broader and less deep posterior excision (ASSING 2008: figure 116). Aedeagus shaped as in ASSING 2008: figures 118-123. Egypt, Sudan (Map 2) .................... .............................................................................................. M. aegyptiacus (BERNHAUER)
- Abdomen with dense and very fine punctation, and with pronounced microsculpture. Head tapering behind eyes, widest across the more convex eyes. Male sternite VIII with short stout modified setae in the middle and with deep and narrow posterior excision. Aedeagus of different morphology....................................................................16
16 Eyes larger and more bulging, strongly projecting from lateral contours of head (ASSING 2008: figures 155-156). Head as broad as long or indistinctly oblong. Male sternite VIII and aedeagus as in ASSING 2008: figures 159, 161-163. Sudan, Yemen (Map 2)............................................................................................... M. sudanicus ASSING
- Eyes somewhat smaller and less bulging (Fig. 10). Head oblong. Male sternite VIII and aedeagus as illustrated in Figs 11-13. Ethiopia (Map 2) ........... M. aethiopicus (CAMERON)
17 Larger species; body length 6.5-7.0 mm; length of forebody 3.5-3.8 mm. Coloration of body dark-brown to blackish-brown. Posterior excision of male sternite VIII broad and moderately deep (Fig. 51). Aedeagus 1.3 mm long and slender, with conspicuous series of long and strongly sclerotized spines in internal sac (Figs 52-55). Malaysia, Thailand, Borneo, Java (Map 4).................................................................... M. suturalis (CAMERON)
- Distinctly smaller and paler species. Posterior excision of male sternite VIII deep and narrow. Aedeagus much smaller, compact, and with completely different internal structures...........................................................................................................................18
18 Preapical antennomeres (VII-IX) transverse (Fig. 33). Pronotum with broadly impunctate midline and laterally with coarser (though shallow) and dense punctation (Fig. 34). Head with fine but transverse microsculpture. Male sexual characters unknown. Myanmar. ......................................................... M. flavescens (MOTSCHULSKY)
- Preapical antennomeres not transverse, usually oblong. Punctation of pronotum different.............................................................................................................................19
19 Head (Fig. 37) at least as broad as long, with marked posterior angles, subparallel behind eyes. Head and pronotum somewhat flattened (cross-section) and distinctly glossy, with sparse and rather distinct punctation. Posterior excision of male sternite VIII very narrow. Aedeagus with long, basally strongly curved, strongly sclerotized, spine-like internal structure in dorsal position..................................................................20
- Head usually oblong, rarely as broad as long, mostly more or less distinctly tapering behind eyes and with more broadly convex posterior angles. Head and pronotum not distinctly flattened, less glossy and with different punctation. Posterior excision of male sternite VIII less narrow. Aedeagus of different morphology..................................21
20 Male sternite VIII distinctly oblong; posterior excision distinctly less than one third the length of sternite (Fig. 39). Aedeagus shaped as in Figs 40-42. Laos, Vietnam, Thailand (Map 4) .................................................................................. M. distortus nov.sp.
- Male sternite VIII very weakly oblong; posterior excision deeper, approximately one third the length of sternite (Fig. 44). Aedeagus shaped as in Figs 45-47. Indonesia: Sumba. ............................................................................... M. sumbaensis (SCHEERPELTZ)
21 Larger species, length of forebody 3.2 mm. Male sternite VIII and aedeagus as in Figs 19-22. Thailand (Map 3). .................................................................... M. siamensis nov.sp.
- Smaller species; length of forebody <3.0 mm. A reliable identification of the following species is possible only based on the morphology of the aedeagus..................22
22 Depth of posterior excision of male sternite VIII distinctly less than one third the length of sternite; aedeagus minute, 0.4 mm long, compact, without conspicuous dorso-apical structure, and with relatively small sclerotized internal structure. Species from India ..........................................................................................................................23
- Depth of posterior excision of male sternite VIII nearly one third the length of sternite; aedeagus> 0.45 mm long, more slender, with conspicuous curved dorso-apical structure, and with large, long, and apically finger-shaped sclerotized internal structure. Species from Thailand, Laos, Malaysia, and Indonesia ....................................24
23 Head usually reddish; slightly darker than pronotum at most. Aedeagus as illustrated in ASSING 2008: figures 150-153. Central and northern India (Map 3)..................................... ..................................................................................................... M. indicus (EPPELSHEIM)
- Head brown to dark-brown, darker than the pale-reddish pronotum. Aedeagus as in Figs 15-16. Northeastern India (Map 3) ........................................ M. nigriceps (CAMERON)
24 Body smaller, length of forebody 2.3-2.6 mm. Head distinctly darker than remainder of body. Aedeagus with ventral process pointed and acute apically; dorso-apical structure short and strongly curved (Figs 26-28). Thailand, Laos, Malaysia (Map 3) ......................... ................................................................................................. M. intermedius (CAMERON)
- Body larger, length of forebody 2.6-2.7 mm. Head mostly reddish, only indistinctly darker than pronotum at most. Aedeagus with ventral process apically bifid in ventral view; dorso-apical structure long and only apically curved (Figs 30-32). Indonesia: Sumba .......................................................................................... M. sutteri (SCHEERPELTZ)
description: Published as part of Assing, V., 2013, On the Palaearctic and Oriental species of Scymbalium and Micrillus (Coleoptera: Staphylinidae: Paederinae), pp. 1479-1520 in Linzer biologische Beiträge 45 (2) on pages 1512-1516, DOI: 10.5281/zenodo.5301289