Diversity of Scydmaeninae (Coleoptera: Staphylinidae) in Upper Eocene Rovno amber
Author
Jałoszyński, Paweł
Author
Perkovsky, Evgeny
text
Zootaxa
2016
4157
1
1
85
journal article
10.11646/zootaxa.4157.1.1
2389f078-1812-4b4e-826a-561cd7e46654
1175-5326
262413
6BF4514A-892F-499F-BC1E-B7920C7A00B0
Cephennodes
(
incertae sedis
) sp.
(
Figs 4
,
65–70
)
Material
studied.
Late Eocene
of
Europe
,
Rovno
amber:
sex unknown; inclusion in an elongate prism of amber
16 mm
long (
Fig. 4
), collection number K-800 (
SIZK
).
Description.
BL
1.35 mm
. Body (
Figs 8–15
) elongate but stout, relatively strongly convex, constriction between pronotum and elytra shallow, pigmentation dark reddish-brown.
Head short, HL
0.18 mm
, HW
0.25 mm
; compound eyes oval, large; vertex and frons weakly convex, confluent and unmodified; supraantennal tubercles indistinct. Antennae moderately long and relatively slender, with three terminal antennomeres forming indistinctly demarcated club; AnL
0.60 mm
; all antennomeres elongate, XI slightly shorter than IX and X combined, slightly broader than X, about twice as long as broad, with blunt apex.
Pronotum in dorsal view (
Figs 65, 68
) semioval with rounded anterior margin, strongly transverse, PL
0.43 mm
, PW 0.53; lateral pronotal carinae (
Fig. 68
;
lpc
) narrowly demarcated from disc; sides rounded; posterior pronotal corners acute; posterior margin shallowly bisinuate; lateral antebasal pits (
Fig. 68
;
abp
) distinct, large but shallow, each located slightly closer to posterior than to lateral pronotal margin. Pronotal disc covered with fine but sharply marked punctures separated by spaces about 2–3 times as wide as diameters of punctures; setae sparse, short and suberect (
Fig. 68
).
Elytra (
Figs 65–66, 68–69
) elongate, oval, more convex than pronotum; EL
0.75 mm
, EW
0.63 mm
, EI 1.20; each elytron with small humeral denticle, subhumeral line indiscernible; basal elytral fovea (
Fig. 68
;
bef
) located slightly closer to lateral margin of large, subtriangular mesoscutellum than to humeral denticle. Punctures on elytra slightly larger but shallower than those on pronotum, with diffused margins, separated by spaces about 1–2 times as wide as diameters of punctures; setae similar to those on pronotum (
Fig. 68
).
Legs (
Figs 66–67, 69–70
) moderately long and slender, unmodified; all tibiae straight or nearly straight.
Remarks.
This specimen can be identified as
Cephennodes
Reitter, 1884
on the basis of the following characters, well observable in the inclusion: the suboval body form (
Figs 65–70
); the subconical and truncated maxillary palpomere IV (
Fig. 70
;
mxp4
); the head lacking occipital constriction and strongly declined; the prothorax with lateral pronotal carinae (
Fig. 68
;
lpc
) and a pair of lateral antebasal pits (
Fig. 68
;
abp
); each elytron with one distinct and setose basal fovea (
Fig. 68
;
bef
); the mesoventral intercoxal process broad (
Fig. 70
;
msvp
) and anteriorly flanked by distinctly demarcated subtriangular impressed areas functioning as procoxal rests; and the metaventral intercoxal process (
Fig. 70
;
mtvp
) broad, short and emarginated.
As discussed previously (
Jałoszyński & Kubisz 2016
), extant species of
Cephennodes
are externally very uniform, and the primary diagnostic characters to define species are associated with male secondary sexual modifications of various body parts and the aedeagus. The subgenera of
Cephennodes
are also defined on the basis of genital characters, and therefore a species that lacks any conspicuous modifications can be assigned to a subgenus only if males are available. The sex of the Eocene species is unknown and all visible body parts of this specimen are unmodified. The habitus of this specimen can be regarded as 'generalized' and typical of many unremarkable extant species. Consequently, the Eocene specimen cannot be reliably distinguished from many similar extant species or unambiguously diagnosed as new, and it is here treated as
Cephennodes
(
incertae sedis
) sp.
The specimen from
Rovno
amber is distinctly smaller than
Cephennodes
sp. recorded recently from Baltic amber (
Jałoszyński & Kubisz 2016
), it is
1.35 mm
long, whereas the Baltic beetle is
1.73 mm
long; they also clearly differ in proportions of body parts (EI 1.20 vs. 1.09 respectively in
Rovno
vs. Baltic amber taxa) and the development of subhumeral lines (long and distinct in the Baltic amber specimen vs. indiscernible in the
Rovno
inclusion). Therefore, these are almost certainly different species.