Megarthrus of China. Part 1. Description of a new species resembling M. antennalis Cameron, 1941 (Coleoptera: Staphylinidae: Proteininae)
Author
Liu, Zhiping
Author
Cuccodoro, Giulio
text
Zootaxa
2020
2020-03-11
4750
2
269
276
journal article
10.11646/zootaxa.4750.2.10
e42d108a-3042-485e-9bd3-6225c1bd14ce
1175-5326
3707291
8B8CFE31-C816-4C59-9DED-C6E0168B9FD3
Megarthrus chujiao
Liu and Cuccodoro
,
sp. nov.
(
Figs. 3–29
)
Type material.
Holotype
, male “
China
: N-Sichuan [CH12-26],
70km
N Songpan
, road S 301, above
Gan lake
,
33°15’26’’N
,
103°46’03’’E
,
2700m
, spruce forest with birch, litter, mushroom, moss, and dead wood sifted,
12.VIII.2012
,
M. Schülke
” (cSch).
Paratypes
: same data as holotype,
6 males
, in cSch,
MHNG
and
SWUC
; “
China
[26]—N-Sichuan, N Songpan,
33°15’26’’N
,
103°46’03’’E
,
2700m
, spruce forest with birch,
12.viii.2012
,
V
. Assing”,
2 males
in cAss and
MHNG
; “
China
, W-Sichuan (13) Daxue Shan, Hailuogou Glacier Park, Camp 1,
2100m
,
29°36’00’’N
,
102°03’35’’E
, 27.–
31.05.1997
,
M. Schülke
”,
1 male
and
1 female
, in
MHNG
and cSch; “
China
:
Sichuan
, Gongga Shan, above Camp 2 [
29°57’ N
,
102°00’ E
],
2850m
,
26.VII.1994
,
A. Smetana
, [C25]”,
1 male
, in
MHNG
; “
China
:
Yunnan
: [CH07-28], Nujiang Lisu Aut. Pref., Gaoligong Shan, side valley
19km
NW
Liuku
,
25°59’02’’N
,
98°42’23’’E
,
2730m
, devast, prim, forest, litter sifted,
9.VI.2007
,
A. Pütz
”,
4 males
, in
MHNG
and cPüt
.
Description.
Habitus as in
Figs. 3–4
. Combined length of head, pronotum and elytra
1.8–2.1 mm
; maximal pronotal width=
0.9–1.1 mm
. Body and appendages predominantly rust brown, with head darker. Pubescence on frons convergent, with medial setae directed backward; metaventral setae slightly shorter than proventral setae, becoming longer anteriorly; pubescence on abdominal tergites IV–VII convergent; that on sternites IV–VII with few longer setae posteromedially, but apparently lacking macrosetae. Frons and vertex finely granulate; pronotum and elytra granulo-fossulate; prohypomera almost smooth; metaventrite coarsely punctate laterally, almost smooth in middle.
Frons above clypeus forming sharp ridge, the latter not carinate; mesal portion of disc weakly convex in lateral view, evenly; U-shaped frontal impression shallow. Temples abruptly narrowed just behind eyes, almost smooth. Occipital ridge indistinct. Antenna (
Fig. 25
) with scape rather conical, not compressed; short and dense pubescence present only on antennomeres 5–11; antennomere 11 evenly expanded on basal two-thirds and apically rounded, slightly compressed. Pronotum (
Fig. 27
) with hypomera lacking transverse ridge. Scutellum with anterior margin rounded. Elytral disc without notable relief.
Male
. Frontoclypeal area, protarsomeres 5, metaventrite and abdominal sternites 4–6 unmodified. Protarsomeres 1 possessing ventral patch of modified adhesive setae. Metatarsomere 1 about 1.3 times as long as combined length of metatarsomeres 2–4. Peg-like setae absent from protrochanters, metatrochanters and metafemora; arranged disjunctly in 1–2 rows on protibiae (
Figs. 16–17
); grouped in a field on mesotrochanters (
Figs. 12–13
); arranged in two rows on mesotibiae (
Figs. 18–19
); arranged a in single row on metatibiae, the latter prolonged apically by cluster of long setae (
Fig. 20
). Abdominal tergite VIII as in
Figs. 7, 10
; sternite VIII as in
Fig. 11
; hemitergites IX as in
Fig. 15
; sternite IX without subbasal medial protuberance. Aedeagus as in
Figs. 5–6, 8–9
.
FIGURES 1–4.
Megarthrus
, habitus, male;
Megarthrus antennalis
: dorsal (1) and ventral (2) views;
Megarthrus chujiao
sp. n.
: dorsal (3) and ventral (4) views. Scale bar=0.5 mm.
FIGURES 5–10.
Megarthrus chujiao
sp. n.
(male): aedeagus in lateral (5, 6) and ventral (8, 9) views; abdominal tergite VIII in lateral (7) and dorsal (10) views. Scale bar=0.1 mm.
FIGURES 11–21
.
Megarthrus chujiao
sp. n.
: male, abdominal sternite VIII in ventral view (11); mesotrochanter in ventral view (12); mesofemur and mesotrochanter in lateral view (13); metafemur and metatrochanter in lateral view (14); hemitergite IX (15); protibia in lateral (16) and ventral (17) views; mesotibia in lateral (18) and ventral (19) views; metatibia in lateral (20) view; Metatarsi (21). Scale bar=0.1 mm.
FIGURES 22–29.
Megarthrus chujiao
sp. n.
: female, genital segments, ventral part in dorsal (22) and lateral (23) views, and dorsal part (24) in ventral view; antenna (25); female abdominal sternite VIII in dorsal view (26); outline of pronotum (27); female abdominal tergite VIII in dorsal (28) and lateral (29) views. Scale bar: a, c=0.1 mm; b=0.2 mm
Female
. Abdominal tergite VIII (
Figs. 28–29
) without medioapical projection; sternite VIII as in
Fig. 26
. Genitalia (
Figs. 22–24
) with membranose dorsal part of genital segment slightly sclerotized in middle and dark yellow; gonocoxal plate without dorsal or ventral medial ridges.
Comparisons and diagnostic notes.
Megarthrus chujiao
and
M. antennalis
(
Figs. 1–2
) are the only members of the genus to have the metatibia prolonged apically by a cluster of long seta in the male. They are also the only Oriental
Megarthrus
to possess protibial peg-like setae in the male. These two species can be easily distinguished by males having the shape of the aedeagal ventral wall evenly narrowed toward apex in
M. chujiao
while it is abruptly narrowed at base in
M. antennalis
, and in females by the presence in
M. chujiao
of a pigmented weakly sclerotized mediobasal area on the dorsal part of genital segment (
Fig. 24
), which is absent in
M. antennalis
(see
Cuccodoro 2003
:
Fig. 7e
).
Distribution and natural history.
Megarthrus chujiao
is endemic to the Hengduan Mountains of
Sichuan
and
Yunnan
provinces in
China
, where it was collected in spruce-birch forests, from sifted leaf litter, mushroom, moss and dead wood, at elevations ranging from
2100 to 2850
m
a.s.l.
Etymology.
The name of the new species means antenna in Chinese.