Taxonomic Studies on Australian Psammoecus Latreille (Coleoptera, Silvanidae, Brontinae)

Two new species of Psammoecus Latreille, 1829 from Australia are described: Psammoecus australis sp. nov. and P. venustus sp. nov. A taxonomic revision and diagnoses for other Australian species are provided. Psammoecus obesus Grouvelle, 1919 is recorded from Australia for the first time. Two new synonyms are discovered: Psammoecus t-notatus Blackburn, 1908 = P. amoenus Grouvelle, 1912 syn. nov.; Psammoecus vittifer Blackburn, 1903 = P. concolor Grouvelle, 1919 syn. nov. A lectotype is designated for Psammoecus concolor Grouvelle, 1919.


Material and methods
Observations and measurements were made using an Olympus SZX16 stereo microscope. Habitus photographs were taken with Canon EOS 650D and EOS 7D Mark II digital cameras and a Canon MP-E 65 mm macro objective. Higher magnifications were obtained with Mitutoyo M Plan Apo objectives (10 × and 20 ×), with Asahi Takumar 200 mm and Carl Zeiss MC Sonnar 135 mm telephoto lenses as converging lenses. Photographs of genitalia were taken with Canon EOS 650D and EOS 7D Mark II digital cameras attached to an Olympus CH microscope. Images and image layers were processed with Zerene Stacker (Version 1.04), Adobe Lightroom 5.7 and GIMP (ver. 2.8.0) software.
A total of 383 specimens were studied.
Measurements were taken as follows: length, from apical margin of clypeus to apex of elytra; head width, across eyes; head length, from apical margin of clypeus to an imaginary line between hind margins of eyes; eye length, from anterior to posterior margin; antennal length, from base of 1 st antennomere to apex of 11 th antennomere; antennomere proportions were derived from actual measurements; pronotal width, across maximum width, excluding spines; pronotal length, from anterior to posterior margin; widths of anterior and posterior pronotal margins, across anterior and posterior denticles, respectively; elytral width, across maximum joint width; elytral length, along suture including scutellar shield. Temple angles were measured as described in Karner (2014).
In addition to the definitions proposed by Karner (2014), some further remarks on diagnostic characters are necessary: The shape of the punctures on the vertex and pronotum has considerable diagnostic value. Punctures can be round or narrowed; sometimes they are represented by slit-like, very deep impressions. If punctures are narrowed, the term 'elongate' indicates an elongation in the direction of the body axis (e.g., Fig. 2B, punctation on vertex), while 'widened' indicates an elongation perpendicular to the body axis (e.g., Fig. 2C, punctation on pronotum).
Assessing the width of elytral striae (i.e., the width of strial punctures) can be difficult due to the presence of darkened areas surrounding the individual punctures. The width of these areas does not indicate the actual width of the striae. The strial puncturation should therefore be assessed under oblique, diffused illumination. Strial width in the sense of this work is the width of rows of punctures as indicated by the impressed area of the elytral surface.
Male genitalia vary greatly in shape and in the degree of sclerotization. It was found that strongly sclerotised types often have a more complex three-dimensional structure, whereas weakly sclerotised types are in general dorso-ventrally flattened. Lateral views of male genitalia are only provided if important diagnostic characters were found. Accordingly, both ventral and dorsal views are only depicted if the ventral aspect alone does not provide a sufficiently clear view of the shape of the median lobe.
For holotypes and type material of previous authors, label data are given verbatim, including atypical use of punctuation and spaces. The labels are cited beginning with the uppermost one, the respective lines of text are separated by '|'. Comments on label colours, label shapes, etc., regarding the respective specimen are included in square brackets. Data are condensed for paratypes of newly described species and for other material.

Diagnosis
The following combination of character states distinguishes this species: body oval ( Fig. 1A) length 1.97-2.73 mm; eyes ( Fig. 1B) large, evenly rounded; temples distinct, narrowed evenly immediately behind eyes; frontal grooves flat, slightly curved, short, reaching anterior fifth of eyes; antennae stout ( Fig. 1C), antennomere 6 sometimes slightly darkened, antennomeres 7 -10 distinctly darkened, antennomere 11 whitish yellow; punctation on head and pronotal disc dense, microsculpture absent, punctures round, somewhat smaller than an eye facet diameter, pubescence on head and pronotum moderate; pronotum ( Fig. 1B) widest at anterior third, pronotal punctation moderate, punctures widened, about as wide as eye facet diameter, lateral pronotal margins with four, sometimes only three teeth of moderate size, anterior and posterior denticles present, small; elytra ( Fig. 1A) widest at middle, elytra with piceous maculae: wide band near middle, posterior half of suture and elytral apex darkened, humeral area often slightly to distinctly darkened; elytral pubescence short, longer setae along anterior half of interstice between 9 th and 11 th stria; male genitalia ( Fig. 1D-F) moderately sclerotised, with short, blunt median lobe that bears distinct, complex sclerotizations in apical part of internal sac, parameres short, bearing three distinct, long setae, parameres fused with tegmen, inner margins fused medially at flat angle, almost forming arc.

Distribution
Psammoecus cruciger has been found in Australia (Queensland), Malaysia and Papua New Guinea.

Remarks
The colouration of this species is rather variable, but the general pattern remains constant. A very distinct character is the peculiar shape of the male parameres, which differs considerably from all other known species of Psammoecus. Grouvelle, 1919 Fig. 3 Psammoecus obesus Grouvelle, 1919: 11.

Diagnosis
The following combination of character states distinguishes this species: body elongate-oval ( Fig. 3A), length 3.08-3.29 mm; eyes large ( Fig. 3B), irregularly rounded with stronger curvature posteriorly; temples distinct, short, strongly curved; frontal grooves distinct, diverging anteriorly, parallel near end; reaching anterior 2/5 of eyes; antennae stout ( Fig. 3D), antennomere 8 slightly darkened, antennomeres 9-10 darkened, antennomere 11 bright yellowish-brown; punctation on vertex moderate, punctures distinctly elongate, as large as eye facet diameter; microsculpture on vertex absent, pubescence moderate; pronotum widest just in front of middle (Fig. 3C), lateral pronotal margins with five teeth; tooth I slightly and tooth V distinctly bigger than II-IV, distance between I and II wider than distances between other teeth, anterior and posterior denticles present, small; pronotal punctation dense, punctures as large as on vertex, distinctly widened, microsculpture absent, pubescence moderate, setae directed medially; elytra widest at middle (Fig. 3A), with transverse brown maculae behind middle, interstices distinctly wider than striae, pubescence moderate, microsculpture absent; male genitalia ( Fig. 3E-H) strongly sclerotised, median lobe in dorsal view wide, narrowed abruptly near ostium, apical end well rounded, in lateral view also narrowed abruptly, with sharp apical end; parameres in ventral view very wide, inner margins, apex and apical third of lateral margins with distinct setae; in lateral view with very wide basis, narrowed abruptly towards apex with dorsal margin almost forming angle.

Distribution
The species has been found in Australia (Queensland) and Indonesia.

Remarks
Psammoecus t-notatus is closely related to P. trimaculatus Motschulsky, 1858 and P. triguttatus Reitter, 1874. Most specimens can easily be recognised by their distinct colouration/colour pattern. The determination of unusually coloured specimens requires examination of male genitalia. Psammoecus t-notatus differs from P. trimaculatus by the distinctly longer apical part of the parameres; it differs from P. triguttatus by the elongate, slender median lobe and the large, wide basal part of the tegmen.
Psammoecus t-notatus has a remarkably large area of distribution. As for other species of the genus, records from Malaise traps and at light suggest high mobility and a tendency to accumulate near human settlements. This, combined with an association with plant detritus and/or fungi, is likely to facilitate distribution by human trade of agricultural goods. Blackburn, 1903 Fig. 5 Psammoecus vittifer Blackburn, 1903: 155. Psammoecus concolor Grouvelle, 1919: 8. Syn. nov.

Material examined
Types AUSTRALIA • 1 ♂, holotype of Psammoecus vittifer Blackburn, 1903 Of P. concolor, Grouvelle (1919: 8) mentions two type specimens from Java in the collection of the NHMUK. Only one syntype (♀) could be located in the NHMUK collection; a further syntype (♂) with identical data is stored in the MNHN collection, indicating that Grouvelle kept one specimen for his own collection. The MNHN specimen is hereby designated as lectotype.

Distribution
This species was found in Australia (Queensland), Indonesia, Papua New Guinea and Thailand.

Remarks
Psammoecus vittifer is easily identified by its general habitus and the very distinct structure of the male genitalia. One specimen from Papua New Guinea in the MSNG collection is labelled as "Psammoecus ocularis ty. Grouv." in Grouvelle's hand. This name was never published, hence P. ocularis is considered a manuscript name.

Diagnosis
The following combination of character states distinguishes this species: body length 1.96-2.45 mm; eyes very large, evenly rounded; temples extremely short, strongly narrowed immediately behind eyes; frontal grooves diverging posteriorly, reaching middle of eyes; punctation on vertex very sparse; pronotal punctation sparse; pronotal teeth long; lateral pronotal margin simple; lateral elytral interstices with very long setae; median lobe wide, apex blunt, rounded; parameres short, roundish.

Etymology
The specific epithet is derived from the continent name Australia.  between 9 th and 11 th stria with distinct denticles near humerus; microsculpture absent. Male genitalia (Fig. 6E-G) with wide median lobe, apex evenly rounded, in the shape of a half-circle, parameres short, stout, almost circular in ventral view, each with one very long and several shorter setae.

Biology
The species was found in flight intercept traps, in berlese funnels and in plant detritus.

Variation
Paratypes range in length: 1.96-2.45 mm. The elytral maculae differ considerably in size. In some specimens, only the 11 th antennomere is whitish.

Remarks
Psammoecus australis sp. nov. is closely related to Psammoecus delicatus Grouvelle, 1908 andPsammoecus complexus Pal, 1985. It can be distinguished from P. complexus by the distinctly different colouration, and from both species by the different shape of lateral pronotal teeth and male genitalia.

Etymology
The specific epithet was chosen in reference to the beautiful habitus of this species.  1.04 mm wide, striae about as wide as interstices, pubescence strial setae 1/3 to 1/2 as long as interstrial setae; lateral insterstices with very long, erect setae; microsculpture absent. Male genitalia (Fig. 7E-G) with slender, lancet shaped median lobe, internal sac with numerous small denticles and long, curved ductus; parameres long, slender, parallel-sided, slightly curved medially, with two large apical setae and numerous setae along the inner margins.

Variation
Paratypes range in length from 2.32 mm to 3.14 mm. The elytral colouration varies considerably in the size of the dark maculae, but with the general pattern of colouration present in all specimens. The colour of head and pronotum ranges from entirely testaceous to piceous. The 10 th antennomere is often whitish, like the 11 th .

Biology
The species was found on plants, in plant detritus, in flight intercept and pitfall traps and and only once at light.

Remarks
This species somewhat resembles Psammoecus felix (Waterhouse, 1876), described from Sri Lanka. Psammoecus venustus differs distinctly in colouration, in the shape of the male genitalia, and in the structure of the frontal grooves.

Discussion
The present paper is the first to provide a revision of all species of Psammoecus known from Australia. It records seven species, two of them new to science and one new to Australia. Surprisingly to the author, no Australian specimen of Psammoecus trimaculatus was among the numerous specimens that were studied, even though it is a very widely distributed species, most likely by human trade (see Mola & Yoshida 2019 for an overview on the current knowledge about its distribution).
Several species of the genus show extraordinarily large areas of distribution (Mola & Yoshida 2019;Yoshida 2018). The three exclusively Australian species (P. australis sp. nov., P. venustus sp. nov., P. incertior) do not represent a distinct group within the genus, and a look at all seven species reveals a quite typical representation of Psammoecus diversity. It can not be ruled out that the current Australian fauna of Psammoecus is a mixture of mostly imported species. Human trade is likely an important factor for the spread of many species of Psammoecus (see also Lu & Han 2006;Ouellette 2018); their association with plant detritus and high flight activity corroborates this hypothesis.
However, the generally poor knowledge about the genus and lack of faunistic data do not allow for more than speculation. Future studies on the Psammoecus of Australia and adjacent areas might shed light on this question.