(Proceedings submission caseby-case

DEUVE ET AL.: CARABID BEETLE FAUNA OF THE GAOLIGONG MOUNTAINS 381
Trechus we have examined from the Gaoligong Shan, which all show a trifid state (Fig. 16b-d).
However, in members of a very specific and homogeneous group of species in the study area, the
right mandible has dentition of another type: the premolar tooth is incompletely fused with rétinacle
(a relatively symplesiomorphic condition) and the anterior tooth of the retinaculum is located
forward (a synapomorphy), a greater distance from the posterior tooth (Fig. 16f). Members of this
group of species also present two additional remarkable features. First, there is only one or no discal
setae on elytral interval 3; and second, the tempora are sparsely pubescent, whereas they are
glabrous in all other “Trechus” of the Gaoligong Shan region. Members of some species in Tibet,
such as Trechus setitemporalis Deuve (2005), or those of the “Trechus dacatraianus Group”
(Schmidt 2009), also have pubescent tempora. However, it is the combination of the three states
mentioned above, especially the mandibular structure, which leads us to exclude these species from
Trechus and consider them as representing a distinct genus within the Epaphiopsis Complex of
genera. Descriptions of this genus and the included species are provided below. A related species,
but one in which members have the tempora glabrous and the premolar and retinaculum of the right
mandible (Fig. 16h) more fully fused, is also excluded from Trechus and described as a separate
genus. Finally, we also exclude two additional species from the southern part of the Gaoligong
Shan from Trechus. In members of these species, the right mandible (Fig. 16g) is very similar to a
bidentate type, but the premolar tooth is not fused with the retinaculum. we consider these also as
representing a new and distinct genus described below.
GEOGRAPHICAL DISTRIBUTION.— Genus Trechus is a megadiverse taxon with more than 900
described species and subspecies arrayed in eight subgenera (Lorenz 2005); and about 95% of
these species-group taxa are currently classified in the nominate subgenus. The genus is predominately
Holarctic in distribution and widespread in that Region (Jeannel 1927, Casale & Laneyrie
1982), with a few species also recorded from the Afrotropical and Oriental Regions. Several
species from subtropical or tropical parts of Southeast Asia have been described in genus Trechus.
Examples of such species include Trechus thai Deuve (1995) from Thailand, Trechus myanmarensis
Deuve (2005) and Trechus natmataungensis Donabauer (2010) from Myanmar and Trechus
vietnamicus Uéno (1995) from Vietnam. However, the genus is not known from tropical or subtropical
parts of China, where it appears to be replaced by species representing the Epaphiopsis
Complex of genera.
Key for Identification of Adults of Trechus Species of the Gaoligong Shan Region
1. Size larger (BL = 4.2 to 5.0 mm), fully-winged; elytra elongate, recurrent stria terminated
abruptly on interval 6; preapical seta absent or vestigial and inserted near elytral apex, also
without a third discal seta in apical one-fouth of elytra . . . . . . . . . . . . . . . . T.indicus Putzeys
Size varied, but generally smaller (BL = 3.3 to 4.7 mm), elytra short, recurrent stria continuous
anteriorly with stria 5 or 7, preapical seta present and inserted near stria 2 in a subdiscal
position or as third discal seta near stria 3 in apical one-fourth of elytra (Trechus qiqiensis
Group) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Trechus qiqiensis Group:
2. Elytra with recurrent stria in line anteriorly with stria 5, preapical seta inserted near stria 2; size
moderately large for group (BL = 4.0 to 4.2 mm) (FugongCounty). . T. shiyueliang sp. nov.
Elytra with recurrent stria in line anteriorly with stria 7, preapical seta inserted in interval
3, either near stria 2 or stria 3; size varied. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Size larger, BL at least 4.0 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Size smaller, BL less than 4.0 mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6