First record of Jacobsoniidae (Coleoptera) from China with description of a new species of Sarothrias Grouvelle

Abstract The family Jacobsoniidae Heller (短跗甲科) is newly recorded from China upon the discovery of Sarothrias sinicus Bi & Chen, sp. n. (中华短跗甲) from Motuo, Southeast Xizang. Description and illustrations of the habitus and major diagnostic features of the new taxon are provided. A key to the species of Sarothrias and some ecological notes on the new species are presented.


Introduction
The family Jacobsoniidae Heller, 1926 was considered incertae sedis within the series Bostrichiformia by Löbl and Burckhardt (1988), Lawrence and Newton (1995) and Lawrence et al. (1999a, b).  provisionally placed Jacobsoniidae within the series Derodontiformia, along with families Derodontidae and Nosodendridae. In the current study, the results of a cladistic analysis based on morphological characters of adults and larvae indicated that Jacobsoniidae is sister to part of the Staphylinoidea (Lawrence et al. 2011).
Jacobsoniidae includes 21 known species in three genera: Sarothrias Grouvelle, 1918, Saphophagus Sharp, 1886and Derolathrus Sharp in Sharp & Scott, 1908 (Háva and Löbl 2005). They can be recognized by the minute (0.65-2.5 mm), narrowly elongate (about 2.1-3 times as long as wide), yellowish brown body, an elongate prothorax, lack of a visible scutellum, and markedly elongate metaventrite (at least 2.5 times as long as mesoventrite). All species are poorly represented in collections and little is known about their biology Philips et al. 2002).
Currently, 13 species of Sarothrias have been described (Háva and Löbl 2005;Pal 1998). They are restricted to humid tropical areas which close to the equator with the exception of S. hygrophilus Pal, 1998 from northeast India. They can be primarily defined and separated from Saphophagus by tarsal formula 3-3-3 instead of 5-5-5, and from Derolathrus by antennal club 3-segmented instead of 1-or 2-segmented (Burckhardt and Löbl 1990;. During July to August 2014, the first author participated in an expedition to Motuo (=Mêdog), Xizang, the third time that he visited that area. A small but remarkable beetle collected during this expedition represented an interesting, unexpected result in that it is an undescribed species of Sarothrias which belongs to the Jacobsoniidae -a family so far not recorded from China. In this paper, we describe a new species, Sarothrias sinicus Bi & Chen, sp. n., based on this specimen. An identification key to the species of Sarothrias is also included. Based on Lin and Yang (2012), Jacobsoniidae is the 147 th family of Coleoptera recorded from China. Diagnosis. This new species can be separated from most congeners by the elytra, which are predominantly shiny, and elytral row 5 unimpressed; the pronotum is devoid of squamiform setae. It differs from S. hygrophilus Pal by the elytra, with row 1 largely represented by fine punctures, row 2 interrupted by punctures after basal quarter, and with supplementary series (s1) between rows 3 and 4; the pronotum has secretions on the lateral margins instead of on the side below the protrusions. It also resembles S. papuanus Ślipiński but can be easily distinguished by the elytra, bearing four squamiform setae in the distal half of row 2, row 3 merging with row 2 and with s1 between rows 3 and 4; the pronotum is devoid of secretions.

Sarothrias sinicus
Description. Male (Figs 1-3). Body length 2.20 mm, elongate, convex, darkbrown, dorsal surface largely shiny except whitish secretions in parts of pronotum and elytra; legs, excluded tarsi, pubescent and covered with yellowish secretions except two narrow longitudinal shiny band at both sides of femora and tibiae, tarsi brown; wings fully developed.
Head broader than long, width across eyes 0.45 mm, clypeus smooth, rounded anteriorly, fronto-clypeal suture clearly visible; frons slightly broad anteriorly with sides moderately raised, sparsely and distinctly setigerous punctured; eyes large, rounded, nearly as long as half of head length, coarsely facetted. Antenna length 0.88 mm, scape slightly elongate, antennomeres 2-11 transverse, with secretions on antennomeres 1-8, squamiform setae at apex of scape and on antennomeres 2-10 and normal setae on antennomeres 9-11. Pronotum length 0.67 mm, width 0.48 mm, subparallel-sided, widest near middle; anterior margin rounded; disc with a shallow median groove, extending from the anterior one-fifth to little above base, slightly broad posteriorly; punctures on disc of similar size, shape and distribution to those on head; median groove, lateral margins and one-sixth of pronotal base with secretions. Scutellum invisible.
Elytra length 1.38 mm, width 0.79 mm, fusiform, widest slightly after middle; basal transverse bulge well developed, with subbasal band of secretions on which three subbasal depressions on each elytron, each depression with one squamiform setae posteriorly. Each elytron with striae or fine puncture forming 8 rows and 3 supplementary series (Fig. 4) of which 6 rows and 2 supplementary series are visible in dorsal view; rows 1 to 3 impressed at basal quarter and continued as a row of fine punctures, row 2 once again impressed after middle and connected with row 1 subapically, row 3 joined row 2 at apical one-third, rows 4 and 5 represented by fine punctures and disappearing anterior to apical one-third, row 6 largely impressed but intercepted by single puncture at basal one-third, rows 7 and 8 impressed, of which the former extending subapically and the latter starting at basal quarter and extending half of elytra length; three supplementary series (s1, s2, s3) represented by fine punctures, of which s1 present between rows 3 and 4 which starting at basal quarter and joined row 4 anterior to basal half, s2 (=s in Poggi 1991) present between rows 5 and 6 which starting at basal one-sixth and ending subapically, s3 separate from row 7 at basal two-fifths and ending subapically between row 6 and 7; apical half of row 2 and entire length of row 6 with secretions, of which the former secretionary row with four squamiform setae asymmetrically arranged.
Prosternum and mesoventrite largely covered with secretions. Metaventrite covered with the same secretions after mesocoxal insertions (cavities) and between metacoxal insertions, other parts shiny with very sparser and fine punctures; with deep median impression in apical half which with rounded sides and not delimited by lateral ridges. Legs moderately long, tarsi 3-segmented.
Ecological notes. Adult Sarothrias have been collected in leaf litter and rotten wood, but the larvae are as yet unknown . The only specimen of the new species was collected by beating a branch with dead leaves on the way from Baricun (= Bari village) to Renqinbeng (= Renqinbeng Temple), Motuo, Xizang at altitude of 1850 m (Fig. 5). The vegetation types are subtropical evergreen broadleaf forest which has been well protected, although slightly disturbed by locals by grazing. A variety of staphylinids, endomychids and cerambycids were collected at the same time. Another mysterious termitophilous lucanid, Penichrolucanus cryptonychus (Zhang, 1988), which is located in the same area and known only from its original description shares a similar generic distribution with Sarothrias.
Distribution. China: Xizang (Tibet) Autonomous Region, Motuo County. Etymology. The new species is named after the country of the type locality. Secretions on head and pronotum strongly expanded, those on elytra forming longitudinal stripes which are separated by shiny stripes. Rows 2