A revision of Japanese species of the genus Psammoecus Latreille (Coleoptera, Silvanidae)

Abstract Japanese species of the genus Psammoecus Latreille, 1829 are taxonomically revised. Four new species, P. scitus sp. n. (misidentified with P. quadrimaculatus), P. labyrinthicus sp. n., P. boreas sp. n. and P. omotoensis sp. n. are described. Psammoecus bipunctatus (Fabricius, 1792), P. trimaculatus Motschulsky, 1858 (misidentified with P. triguttatus), P. simoni Grouvelle, 1892, P. fasciatus Reitter, 1874 and P. triguttatus are redescribed. Another described species whose distribution in Japan is questionable. P. quadrimaculatus is also redescribed. Lectotype and paralectotype of P. fasciatus and P. triguttatus are designated.


Introduction
The family Silvanidae Kirby 1837 (Coleoptera, Cucujoidea) includes two subfamilies and about 58 genera, approximately 500 species (Thomas and Leschen 2010) and is found around the world: 39 species have been recorded from Japan. The Silvanidae are considered to be fairly primitive among the Cucujoidea (Thomas 2002). Most members of the Silvanidae seem to be fungivorous, and share the character of a large pit for fungal transport called the "mycangium" on each mandible (Thomas 2002). However, Grebennikov and Leschen (2010) stated that these mycangial functions in the Silvanidae had not been verified experimentally. The Silvanidae contain some harmful pests of stored grains and grain products (e.g. Ahasverus advena (Waltl, 1834), Oryzaephilus surinamensis (Linnaeus, 1758) and Silvanus lewisi Reitter, 1876) (Halstead 1986). Some of these species are occasionally transferred with goods in transit and distributed over the world.
The genus Psammoecus Latreille, 1829 (Brontinae, Telephanini) includes about 80 described species and is the second largest genus in the Silvanidae (Thomas and Leschen 2010). Species belonging to Psammoecus were recorded only from the Old World for many years, but one species, Psammoecus trimaculatus Motschulsky, 1858 was found in Brazil recently (Thomas and Yamamoto 2007). In Japan, six described species and four undescribed species of Psammoecus were reported by Hirano (2009) and Hirano (2010). Pal (1985) carried out a historical review of Psammoecus in detail and concluded that Psammoecus belongs to the tribe Psammoecini of the subfamily Psammoecinae. Thomas and Nearns (2008) stated that the correct name of the tribe is Telephanini and that the Psammoecinae should be named Brontinae according to the principle of priority, and Karner (2012) followed this treatment. Lu and Han (2006) reported that Psammoecus triguttatus Reitter, 1874 had been transferred with leather and its packages in transit from China. Therefore, the species belonging to Psammoecus have a potential as important pests and alien species.
The species of Psammoecus are found in plant detritus and they are sometimes attracted to light (Karner 2012), but there is little information on their ecology. In addition, taxonomic studies of Psammoecus are also insufficient and confused, probably for the following reasons: 1) most Psammoecus species were described very early historically; 2) their coloration and the black maculae on the elytra are very variable (e.g. Kreissl 1976;Yoshida and Hirowatari 2013); 3) there are no more than three studies containing descriptions of the genital structures (Pal 1985;Karner 2012;Yoshida and Hirowatari 2013) which provide very useful characters for taxonomic study of the genus (Karner 2012); 4) their body sizes are relatively small, ranging from 1.8 mm to 3.6 mm. In Japan, the classification of Psammoecus has also been confused. For example, Hirano (2009) and Hirano (2010) reported four undescribed species from Japan and stated that the species illustrated as P. triguttatus by Nakane (1963) seemed to be an undescribed species. In addition, Hirano (2009) and Hirano (2010) suspected the authenticity of records of P. trimaculatus from Japan. Recently, Yoshida and Hirowatari (2013) added a new species, P. hiranoi, to the Japanese fauna.
As stated above, taxonomy of this genus involves many problems and it has a potential to provide important pests and alien species. Hence, the authors here review the classification of Japanese Psammoecus by comparison of morphological characters and seek to resolve the taxonomic problems.

Observation of morphology and dissection and photographic technique
External characters were observed under a stereoscopic microscope (Olympus SZX10). Genital structures were placed on a cavity slide glass with 50% glycerol solution and observed with an optical microscope (Nikon Eclipse E400). The genitalia slide was prepared in the following steps: the removed abdomen was placed in a 200 µl PCR tube filled with 10% solution of potassium hydroxide (KOH) and kept in heated water for about seven minutes. After rinsing in 70% ethanol solution, the abdomen was dissected by cutting its side using fine insect pins. The genitalia were removed and transferred to a cavity slide glass with 50% glycerol solution for observation. After the observation, the genitalia and the abdomen were mounted in Euparal on cover glasses each glued to a piece of cardboard, and pinned with the specimens.
Photographs were taken with digital camera (Canon EOS 7D), and composite images were produced using automontage software Combine ZM. These images were retouched using Photoshop 6.0 (Adobe Systems Inc.)

Terminology, abbreviations and specimen deposition
Technical terms of genital structures follow Lawrence et al. (2010) and Lawrence et al. (2011). Morphological abbreviations are as follows: BL -body length from anterior margin of clypeus to apex of elytra measured along the median line; PL -length of pronotum measured along the median line; PW -greatest width of pronotum including lateral teeth; EW -greatest width of elytra; HL -head length from base to anterior margin of clypeus; HW -head width across eyes; IE -width of distance between eyes.
Pronotum (Figs 3B,C). Subquadrate, PW/PL 1.14-1.32. Punctuation on dorsal surface comparatively sparse, punctuation on ventral surface sparser than on dorsal surface. Pubescence composed of many short setae, and long setae on teeth on lateral margins and anterior and posterior angles. Anterior angles with a few very small protrusions, lateral margins with several small teeth, these teeth variable, slightly longer on lateral margins around anterior and posterior angles, and each posterior angle with very small teeth. Elytra (Fig. 3E). Elongate-oval, EW/BL 0.38-0.51. Rows of punctures narrower than interstices. Pubescence composed of many semi-long medium length setae, and some long erect setae in a row around lateral margins, longer toward anterior portion.
9th abdominal sternite (Fig. 13A). Strut very long, narrow, cut at anterior 3/8, diverging gradually at posterior 1/8, branches comparatively small. Lateral sclerites elongate with small sclerites attached around posterior apical portion. Aedeagus (Fig. 13B, C). Parameres broad, depressed at base, narrowed on inner margins in posterior half, incised around apex, punctuated very sparsely, a few long setae around apex, several short setae on lateral margins and posterior half of inner margins. Phallobase diverging in anterior half, each branch twisted at anterior 1/4. Penis relatively elongate, curved dorsally before apex.  Biological notes. This species is found in piled dead leaves such as Japanese pampas grass Miscanthus sinensis Andersson, Banana Musa sp. and some other kinds of broad-leaved tree. This species is most common in the Nansei Islands.
Etymology. The specific name means 'pretty' and 'beautiful'. This new species has vivid coloration. Remarks. Psammoecus scitus sp. n. has been misidentified as P. quadrimaculatus Reitter, 1874 for a long time. Psammoecus quadrimaculatus was originally described from 'Japonia' (=Japan) by Reitter (1874). Sato (1989) first gave the Japanese name 'Yotsumon-semaru-hiratamushi' to P. quadrimaculatus. Hirano (2009) and Hirano (2010) provided figures of this species as P. quadrimaculatus. However, examination of the holotype of P. quadrimaculatus deposited in BMNH revealed that external characters such as the shape of the teeth on the lateral margins of the pronotum and the male genital structure are distinctly different. ( Diagnosis. This species is similar to P. trimaculatus and P. boreas sp. n., but can be distinguished from the former by the shorter teeth on the lateral margins of the pronotum and from the latter by the shorter body length and the shorter antennae.
Pronotum (Fig. 4B, C). Roundly subquadrate, PW/PL 1.16-1.24. Dorsal surface with strong moderately dense punctuation, denser than that on ventral surface; some punctures on ventral surface in rows. Pubescence composed of many short setae on dorsal surface and several medium length setae on each lateral margin, distance between medium length setae approximately regular. Each anterior angle with several very small teeth, each lateral margin with four similarly sized small teeth, the distance between them irregular and variable; each posterior angle with a small tooth, similar in size to those on lateral margins. Elytra (Fig. 4E). Elongate, EW/BL 0.36-0.47. Rows of punctures almost same width as interstices. Pubescence composed of numerous comparatively short setae, without long setae.
Aedeagus (Figs.13E and F). Parameres club-shaped, wide and thick at bases, each apical portion with a long seta, stick-shaped portions with sparse punctuation and several short setae, lateral portions and inner margins of bases with successions of dense punctures, inner margin of bases with numerous short setae. Phallobase enlarged toward posterior margin from posterior 1/3, anterior margin roundly incised, anterior portion extended. Penis flat, wide, narrowed gradually toward apex, apical portion pointed, apical portion of dorsal part with sparse punctures. Distribution. JAPAN: Hokkaido; Africa; Europe; Russia; Turkestan. Biological notes. This species is known to inhabit marshland. Warne (1963) reported that large numbers of this species were found on Carex.
Remarks. The habitat and distribution of this species are unusual in the genus Psammoecus. This species inhabits marshland and is distributed in comparatively high latitudes where species richness of Psammoecus is poor. Coloration is variable. In the past, four aberrations and two varieties (e.g. Lucas 1843; Gerhardt 1912) were described. Diagnosis. This species is closely similar to P. triguttatus and P. labyrinthicus sp. n. but it can be distinguished from the former by the larger basal parameres and the broader distance between the posterior margin of the phallobase and the deepest point of incision of the anterior margin of the phallobase, and from the latter by the larger bases of parameres and the wider protuberances on the inner margins of the branches of the anterior phallobase. The rows of punctures on the elytra of P. trimaculatus (Fig. 5E) are comparatively narrower than in these two closely similar species. However, their external characters, especially their coloration, are variable. These features may cause misidentification. Description. Body length. 2.32-2.96 mm (n=38). 9th abdominal sternite (Fig. 13G). Strut Y-shaped, elongate, cut at anterior 3/8, diverging in posterior 1/5, branches relatively wide, narrowed gradually toward apex, ends of each branch curved inward. Lateral sclerites elongate, membranous.

Psammoecus trimaculatus
Aedeagus (Fig. 13H, I). Parameres hatchet-shaped, inner margin around bases pointed, punctuated sparsely on stick-shaped portions, densely on anterior portions, a long seta at each apex, numerous short setae on stick-shaped portions and around inner margins of anterior parts. Posterior margin of phallobase rounded, phallobase roundly hollowed, its anterior branches markedly protruding inward. Penis gradually narrowed toward apex, posterior 1/9 flattened, punctuated sparsely on posterior 1/9.   (2012); Nepal, India and Bhutan recorded by Pal (1980).) Remarks. This species was redescribed by Pal (1980) with a description of the larva. It is distributed worldwide except for Europe and North America and common at least in Japan and India (Hirano 2009;Karner 2012;Pal 1980). Hirano (2009) and Hirano (2010) illustrated this species as P. triguttatus and suggested that the distribution of P. trimaculatus in Japan is doubtful. In this paper, it is regarded as P. trimaculatus on the basis of comparison of the male genital structure of the species illustrated by Pal (1985). Pal (1985) gave as the distribution of this species Madagascar, Sri Lanka, Nepal, India, Malaysia, Burma, New Guinea, Australia and Japan, synonymizing the following species with P. trimaculatus: Telephanus cruciger Waterhouse, 1876 and Psammoecus cephalotes Grouvelle, 1919 from New Guinea, Cucujus incommodus Walker, 1859 from Sri Lanka and Psammoecus ypsilon Blackburn, 1903 from Australia (Walker 1859;Waterhouse 1876;Blackburn 1903;Grouvelle 1919). In addition, Thomas and Yamamoto (2007) recorded this species from Brazil. However, in view of the evidence that at least two other closely similar species have been confused with this species, past records of this species should be reexamined. The specimen figured by Thomas and Yamamoto (2007) seems to be another species. In this paper, records of this species from outside Japan are recognised from label data described by Pal (1980) and Karner (2012), on the basis that they examined the male genital structure.
Pronotum (Fig. 6B, C). Broad, PW/PL 1.31-1.50. Dorsal surface with relatively dense punctuation. Pubescence composed of relatively fine short or medium length setae, a long seta on each tooth on lateral margins and anterior and posterior angles. Each anterior angle with four or five small teeth; each lateral margin with four teeth, tooth I small, tooth II longer than tooth I, teeth III and IV relatively narrow and of almost identical size, longer than tooth II, tooth V smallest or absent; each posterior angle with a few very small protuberances of variable shape. Elytra (Fig. 6E). Elongate-oval, EW/BL 0.39-0.45. Rows of punctures narrower than interstices. Pubescence composed of many semi-erect setae of medium length; several long setae in a row around anterolateral margins. 9th abdominal sternite (Fig. 13J). Strut Y-shaped, cut at anterior 2/5. Lateral sclerites curved inward, relatively elongate. Aedeagus (Fig. 13K, L). Parameres club-shaped, wide around bases, posterior inner margins of wide portions a little prominent, punctuation on narrow portions relatively sparse, a little denser on wide portions, posterior half of inner margins of wide portions with many setae, narrow portions with several sparse setae, apex with a long seta. Posterior half of phallobase wider towards posterior margin, distance between posterior margin and deepest point of incision of margin of upper layer narrow, protuberances around anterior 1/4 pointed inwards, posterior margin of lower layer widely deeply incised. Penis relatively flat and thin, narrowed toward apex, punctuation around apex denser toward apex.
Type series. Lectotype: male, Nagasaki, Nagasaki Prefecture, Japan, 1869, G. Remarks. Psammoecus sp. 4 illustrated by Hirano (2009) and Hirano (2010) seems to be this species or P. labyrinthicus sp. n. However, identification is difficult, because the specimen is a female. The Japanese name of Psammoecus sp. 4 given by Hirano (2009) and Hirano (2010) "Nise-mitsumon-semaru-hiratamushi" is adopted as the Japanese name of this species in this paper. Halstead et al. (2007) recorded distribution of this species from Russia (Far East), Korea, China and Japan. However, it is now clear that at least two closely similar species occur in Japan, so, past records of this species should be reconfirmed. In addition, two or more closely similar species were sometimes found in the same limited area such as Tentoku, Toki-cho, Mizunami City, Gifu Prefecture where P. triguttatus and P. trimaculatus were collected. Thus, these species should be identified carefully.
Syntypes of this species consist of two specimens, one male and one female. The male specimen is designated as a lectotype, and the female specimen is designated as a paralectotype.
Pronotum (Fig. 7B, C). Roundly subquadrate, PW/PL 1.25-1.53. Relatively strong and dense punctuation on dorsal surface. Pubescence composed of short setae, a long seta on each tooth on lateral margins and anterior and posterior angles. Each anterior angle with several small teeth, each lateral margin with four short teeth; tooth I small, tooth II longer than tooth I, teeth III and IV almost the same size, longer than tooth II, teeth II, III and IV broadened at base, each posterior angle with a very small tooth, the shape of these teeth variable. Elytra (Fig. 7E). Elongate-oval, EW/BL 0.41-0.47. Rows of punctures narrower than interstices. Pubescence composed of numerous medium length semi-erect setae and some long setae in a row around lateral margins. 9th abdominal sternite (Fig. 14A). Strut relatively short, cut at anterior 1/3. Lateral sclerites fused with strut, curved inwards. Aedeagus (Fig. 14B, C). Parameres stout, club-shaped, punctuated on anterior half of inner margins, anterolateral portions well punctuated, anterior half of inner margins with many setae of variable size, apex with a long seta. Phallobase broadened toward posterior margin, posterior margin widely incised, protuberances around 1/3 of inner margins of branches, especially right protuberance thin. Penis flat, narrowed toward apex, apex pointed, punctuated around anterior 1/8, apex densely punctuated. Biological notes. The first author (Yoshida) collected many individuals of this new species from dead leaves of evergreen trees in Tsushima Island, Nagasaki Prefecture (Fig. 15A).
Etymology. The specific name means 'labyrinthine'. Identification of P. trimaculatus and closely similar species is very difficult. The addition of this new species to this group of closely similar species made their identification more difficult like the labyrinth.
Remarks. Psammoecus trimaculatus is closely related to this species, however the former has been often collected from dead leaves of monocotyledon plant. These two species may have each distinct ecological trait.  : Nakane 1963: 195, fig. 16 in pl. 98. Psammoecus sp. 3, Hirano 2009: 63, 66, 67, fig. 8. -Hirano 2010 Diagnosis. This species is similar to P. trimaculatus and other species closely similar to P. trimaculatus. Nakane (1963) provided a figure of this species as P. triguttatus. It differs from the aforementioned species by the shorter lateral teeth of the pronotum. It is also very similar to P. harmandi Grouvelle, 1912 both in external characters and male genital structure as illustrated by Pal (1980), but can be distinguished from it by the longer antennae and the comparatively oblong 10th antennomere.
Description. Body length. 2.74-3.27 mm (n=19). Coloration ( Fig. 2A). Head and pronotum yellowish-brown. Elytra yellowishbrown with dark brown maculae at half, oval ones at center of each elytron and dark oblique bands toward posterior portion, sometimes connected at elytral suture, forming a V-shaped band. Elytra of lighter color specimens with reduced maculae, oval ones and bands separated. Antennae yellowish-brown basally, posterior ends of 8th to 10th antennomeres darkened, or all antennomeres yellowish-brown in lighter colored specimens.
Pronotum (Fig. 8B, C). Subquadrate, PW/PL 1.18-1.30. Dorsolateral portions lightly impressed. Dorsal surface with relatively dense punctuation, no punctures around posterior margin, comparatively sparse punctuation on ventral surface. Pubescence composed of many short setae and fine long setae on teeth on lateral margins and anterior and posterior angles. Each anterior angle with a distinct group of a few very small teeth, each lateral margin with four small teeth of almost the same size, each posterior angle with a small tooth, almost the same size as those on lateral margins. Elytra (Fig. 8E). Oval, EW/BL 0.32-0.45. Rows of punctures wider than interstices. Pubescence composed of many short setae, no long setae. 9th abdominal sternite (Fig. 14D). Strut Y-shaped, cut deeply at anterior 1/5, diverging for posterior 1/4. Lateral sclerites elongate.
Aedeagus (Fig. 14E, F). Parameres cone-shaped with almost even sparse punctuation, sparser on bases, a few long setae around apical portions, a few short setae distributed sparsely. Phallobase tube-like, consisting of two layers, anterior margin rounded, dorsal surface around anterior margin thin, protuberances of upper layer directed towards  Diagnosis. This species is distinguished from other Japanese Psammoecus species by the black elytra with yellow maculae and the posterior teeth on lateral margins of pronotum longer than those of anterior margins. Description. Body length. 2.24-2.56 mm (n=8). 9th abdominal sternite (Fig. 14J). Strut comparatively short, cut at anterior 2/5, diverging gradually, branches comparatively long and wide. Lateral sclerites elongate, slightly curved inwards, apical sclerites pointed.
Pronotum (Fig. 11B, C). Broad, PW/PL 0.69-1.52. Punctuation on dorsal surface very dense, but no punctures around posterior margin, punctuation on ventral surface sparser than dorsal surface, some of them in rows especially on posterior half. Pubescence composed of frequent short setae on dorsal surface and a long seta on each tooth on lateral margins and at anterior and posterior angles. Each anterior angle with a distinct group of a few very small teeth, each lateral margin with four teeth; tooth I comparatively small, teeth II, III and IV almost the same moderate size, each posterior angle with a comparatively small tooth. Elytra (Fig. 11E). Elongate-oval, EW/BL 0.41-0.47. Punctures wider than interstices. Pubescence composed of semi-erect medium length setae and some long erect setae in a row around lateral margins, longer toward anterior portion.
Aedeagus (Figs 14N and O). Parameres simple stick-shaped, elongate, slightly curved inwards, punctuated sparsely except base, a few semi-long setae around apical portion. Phallobase diverging gradually around anterior 1/4, a little bulging along inner margins of each branch, lateral margins broadening. Penis also elongate, punctuated on posterior 1/6, more densely on ventral portion, especially densely on apical portion. Remarks. Yoshida and Hirowatari (2013) described this species from the Nansei Islands, Japan including Nakanoshima (Tokara Islands), Amami-Ôshima, Tokunoshima, Okinawa, Ishigaki and the Iriomote Islands. It is closely similar to P. fasciatus, and these two species occur allopatrically across the Watase Line, which is one of the biogeographic borders proposed between the Palaearctic and Oriental regions passing through the Tokara Straits (Yoshida and Hirowatari 2013). Yoshida and Hirowatari (2013) described this species and regarded the undetermined species, Psammoecus sp. 2 of Hirano (2009) andHirano (2010), as conspecific. In addition, in the present study, Psammoecus sp. 1 illustrated by Hirano (2009) and Hirano (2010), which was represented by only one female, is also found to be conspecific with this species. We had the opportunity to examine some specimens possessing features of Psammoecus sp. 1 (Fig. 2E) and were able to conclude that morphological characters including the male genital structure of these specimens belonged to the range of morphological variation of P. hiranoi.
The following specimens were found after description of this species: Diagnosis. This species is similar to P. trimaculatus, P. triguttatus and P. labyrinthicus sp. n., but can be distinguished from P. trimaculatus and P. triguttatus by the wide triangular basal portion of the parameres and the apically narrow portion of the penis, and from P. labyrinthicus sp. n. by the longer parameres, the apically narrow portion of the penis and the shape of the phallobase. Description. Body length. 2.50 mm (n=1). Coloration (Fig. 2F). Head reddish-brown, pronotum somewhat light reddishbrown. Elytra blackish-brown with four large yellowish-brown maculae; macula around anterior 1/4 of each elytron almost quadrate, macula on posterior half longer than wide. Antennae yellowish-brown basally, 6th to 10th antennomeres black, 6th slightly brighter, 11th (apex) bright.
Pronotum (Fig. 12B, C). Roundly subquadrate, PW/PL 1.34. Punctuation on dorsal surface relatively strong and moderately sparse. Pubescence composed of medium length setae, a long seta on each tooth on lateral margins and anterior angles, a relatively long seta on each posterior angle. Each anterior angle with several small teeth, each lateral margin with four short teeth; tooth I small, tooth II longer than tooth I, teeth III and IV almost same size, longer than tooth II, teeth II, III and IV relatively widened around base, each posterior angle with a few very small teeth. Elytra (Fig. 12E). Elongate-oval, EW/BL 0.46. Rows of punctures wider than interstices. Pubescence composed of many medium length semi-erect setae, long erect setae in a row on lateral margins. 9th abdominal sternite (Fig. 14P). Strut cut at anterior 1/3, diverging deeply around posterior 1/3. Lateral sclerites rhomboid, comparatively large, curved inwardly. Aedeagus (Fig. 14Q, R). Parameres club-shaped; narrow portions relatively broad, punctuated sparsely, with several sparse setae , apex with a long seta; wide portions punctuated densely on posterior half of inner margins and anterolateral portions of outer margins, posterior half of inner margins with many setae. Phallobase consisting of two layers, posterior margin incised roundly, distance between posterior margin and deepest point of incision of margin of upper layer narrow, anterior margin of lower layer relatively narrowly incised, protuberances around anterior 1/4 narrow, projecting inwards, posterior margin of lower layer broadly incised. Penis relatively elongate and flat, with relatively dense punctuation on posterior 1/8. Type series. Holotype: male, Nagasaki, Nagasaki Prefecture, Japan, 1869, G. Lewis leg. (BMNH).
Distribution. JAPAN: Nagasaki?. Remarks. Type specimen was mounted with a label reading 'Nagasaki | 1869 | ? imported in Rice -'. We have not been able to find any specimen of this species from Japan other than holotype. Hence, occurrence of this species in Japan seems to be questionable.