Revision of the genus Intybia (Coleoptera, Malachiidae) from Japan

Japanese species of the genus Intybia are revised taxonomically, with the examination of the endophallic structure. Eight species, including one new species Intybia donan sp. nov. from Yonagunijima, are recognized. All species are described or redescribed with a key and fi gures. The endophallic structure contains one primary sclerite (gonoporal piece), three secondary sclerites (ligula, semigonoporal piece, and spinous plate) in some species, and a membranous basal area densely covered with many spines (spinous area). Based on the structures of the endophallus, the Japanese members of the genus are divided into two species groups (the histrio and pelegrini groups). The pelegrini species group is furthermore subdivided into three subgroups (subgroups 1–3). New distributional records are as follows: I. histrio from Hachijô-jima and Tanega-shima; I. niponica from Sakhalin and I. takaraensis from Tokuno-shima and Amami-Ôshima.

EW = maximum width of elytra GL = length of gonoporal piece HL = head length HW = head width across eyes L = length of antennomere III LL = length of ligula PL = length of pronotum in median line PW = maximum width of pronotum SGL = length of semi-gonoporal piece TL = total length (HL + PL + EL) W = width of antennomere III The average is given in parentheses after the range.  Pascoe, 1866].

Remarks
This species closely resembles Intybia tsushimensis (Satô & Ohbayashi, 1968), and is distinguished from the latter by the coloration and structure of the endophallus. These species are distributed allopatrically.

Biological notes
This species is the most common in mainland Japan. It inhabits forest edges and grasslands (Fig. 12A), and can be collected from shrubs and bushes by sweeping and beating.

Remarks
The species is similar to Intybia histrio (Kiesenwetter, 1874) in the shape of the male antennomere III, elytral coloration and endophallic structures, and differs from it in the coloration of the legs and antennae, and in the shapes of the semi-gonoporal piece and ligula. This species seems to be endemic to Tsushima Is.

Biological notes
This species inhabits forest edges and grasslands, and can be collected from shrubs and bushes by sweeping and beating.

Diagnosis
Elytra with four pale yellow spots; antennomere I long, abruptly widened from near the middle; antennomere III ginkgo-like shaped, two concavities on outer edge and provided with a slender tonguelike projection near base; gonoporal piece gently curved, constricted near the middle; semi-gonoporal piece slightly curved; ligula long, slightly curved; spinous plate absent.

Etymology
After the old name of the type locality Yonaguni-jima.

Description
Male Body (Fig. 1C) oblong oval, shining, densely covered with yellow pubescence, and sparsely covered with long erect hairs. Coloration of head, pronotum and elytra black; antennae, two pairs of elytral spots, and legs pale yellow.

Remarks
This species is distinct in having a small body and four elytral spots. It is similar to Intybia viridithorax (Pic, 1921) in the shapes of antenna and male genitalia (Wittmer 1997), and differs from the latter by the coloration of the elytra with four spots (I. viridithorax has fascia).

Biological notes
This species is rare, inhabits forest edges (Fig. 12C), can be collected from the fl owers of Ardisia sieboldii Miquel and Meliosma oldhamii Miquel ex Maximowicz (Fig. 12D), and can be collected from shrubs and bushes by sweeping, beating, and light traps.

Diagnosis
Elytra with a wide yellow fascia just before the middle, which is widened on lateral margin, and indented posteriorly; antennomere III half crescent-like shaped, excavate on upper surface; gonoporal piece straight, slender, slightly curved basally; semi-gonoporal piece and ligula absent, with two spinous plates.

Remarks
This species is distinct in having a slender body shape, a characteristic coloration, a special shape of the male antennomere III, and two spinous plates. Wittmer (1997) described the subspecies, I. pelegrini longior Wittmer, 1997, for the Korean population, and this subspecies differs from the nominotypical subspecies (= Japanese population) by the male antennomere III more elongate by 15-20% (Wittmer 1997).

Biological notes
This species inhabits grassland areas near large rivers.

Diagnosis
Elytra with a yellow fascia, widened at suture and lateral margins; antennomere III broad bean-like shape excavated on dorsal surface; gonoporal piece straight, slender; semi-gonoporal piece and ligula absent; one spinous plate present.

Remarks
Female is apterous. The specimens from Hokkaido have a larger body, but the other features are quite the same as other specimens.

Biological notes
The larva of this species was described in detail by Asano (2013) and showed foetometamorphosis. This species inhabits beach plant communities (Asano 2013), and can be collected by sweeping beach plants (Fig. 12B).

Remarks
This species is closely similar to Intybia niponica (Lewis, 1895), and differs from it in the coloration of the body with a bluish luster and the shape of the male antennomere III.

Biological notes
This species inhabits beach plant communities or grasslands areas near large rivers.

Diagnosis
Coloration of head, pronotum and elytra black with bluish luster; head narrow; eyes not prominent; elytral fascia reddish orange, widened at suture and lateral margins; gonoporal piece straight, slender, with straight basal projection; semi-gonoporal piece, ligula and spinous plate absent.

Remarks
This species is rare and no additional specimens besides the type series have been collected. This species was recorded from Kyushu by Satô (1989) and Yoshitomi & Hayashi (2011), but we regard this as a simple mistake.

Biological notes
The type series was collected from the northernmost cape of the island, and this species probably inhabits beach plant communities.

Discussion
The genus Intybia is divided into some species groups (Wittmer 1997;Plonski & Geiser 2014). Wittmer (1997) regarded the seven Japanese species as being included in the pelegrini species group (= Gruppe 2). Based on the construction of the endophallic structure in the seven species (except for I. kawasakii, for which the endophallic structure could not be examined), the Japanese species are divided into the following two species groups: The histrio group (histrio, tsushimensis, donan) This group is proposed here, and is characterized by the following structures: male antennomere III with a projection near the base; elytra fascia does not widen at the suture; endophallic sclerites are composed of one gonoporal piece, one semi-gonoporal piece, and ligula; spinous plate absent.
The pelegrini group (pelegrini, niponica, takaraensis, kishiii) This group was proposed by Wittmer (1997) for 26 Asian species and is redefi ned in this paper. It is characterized by the following structures: male antennomere III with or without a projection near the base; elytra fascia widened at the suture; endophallic sclerites composed of one gonoporal piece and 0-2 spinous plate(s); semi-gonoporal piece and ligula absent. Intybia kawasakii is expected to belong to this species group from the shape of the antennomere III.