Psammoecus labyrinthicus, Yoshida, Takahiro & Hirowatari, Toshiya, 2014

Yoshida, Takahiro & Hirowatari, Toshiya, 2014, A revision of Japanese species of the genus Psammoecus Latreille (Coleoptera, Silvanidae), ZooKeys 403, pp. 15-45: 28-29

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Psammoecus labyrinthicus

sp. n.

Psammoecus labyrinthicus   sp. n. Figs 1E, 7and 14 A–C


This species is closely similar to Psammoecus trimaculatus   and Psammoecus triguttatus   . However, it can be distinguished by the male genital structure, especially the shape of the parameres, and the comparatively dense punctuation of the dorsal pronotum.


Body length: 2.66-3.38 mm (n=25).

Coloration (Fig. 1E). Head and pronotum reddish-brown. Elytra yellowish-brown with dark maculae; round ones at half, oblong ones on the posterior half to posterior 1/4 along elytral suture, darkened around end of elytra: these maculae sometimes connected each other. Antennae reddish-brown basally, 7th antennomere darkened, from 8th to 10th blackish-brown, 11th (apex) comparatively bright.

Head (Fig. 7A, B, C). Rounded-triangular, HW/HL 1.25-2.00; IE/HL 0.75-1.27. Temples slightly expanded behind eyes, gradually narrowed. Eyes large, prominent. Dorsal surface with dense and strong punctuation. Antennae 1.35-1.56 mm, moderately long; covered with medium length semi-erect pubescence and some long erect setae on each antennomere; approximate ratio of holotype as follows: 2.4: 1.0: 1.0: 1.2: 1.3: 1.1: 1.1: 1.1: 1.1: 1.1: 1.9 (Fig. 7A).

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.

Type series.

Holotype: male, Hachijô Island, Hachijô Town, Tokyo Prefecture, Japan, 21 –VII– 1957, S. Hisamatsu leg. (EUMJ). Paratypes: [Tokyo Pref.] 3 females, same data as holotype. (EUMJ). [Mie Pref.] 4 males, Ujitachi-chô, Ise City, 29 –VIII– 2009, N. Narukawa leg. (ELKU). [Nagasaki Pref.] 1 male and 11 exs., Ta, Toyotama-chô, Tsushima Island, 7 –VII– 2013, T. Yoshida leg. (ELKU). [Kagoshima Pref.] 2 males and 3 exs., Takarajima Island, Toshima Village, 2 –VII– 1960, M. Satô leg. (EUMJ); 1 ex., same locality, 3 –VII– 1960, M. Satô leg. (EUMJ); 1 ex., same locality, 1 –VI– 1962, M. Satô leg. (EUMJ).


JAPAN: Honshu, Hachijô (Izu Islands), Tsushima, Takarajima Islands (Tokara Islands).

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).


The specific name means ‘labyrinthine’. Identification of Psammoecus 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.


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.