Chaetabraeus (Mazureus) sp.

Epiechinus arboreus (Lewis, 1884)

Japanese name: Chibi-ke-sesuji-emmamushi

Onthophilus arboreus Lewis, 1884: 139 [Japan: Honshu: Nara].

Epiechinus arboreus: Lewis, 1891: 320; Hisamatsu, 1985: 226, pl. 4, f. 1.

Scolytus arboreus: Jakobson, 1911: 652.

Epiechinus arboreus: Ohara, 1994, 85.

Original description.

"Orbicularis, niger, hispidus, opacus; antennis clava ferruginea. O. hispido proxime affinis, sed minor. L. 1.1/2 mill."

Redescription. (Ohara, 1994)

Body oval, dark brown, furnished with minute spines and usually covered with mudlike scales. Body length, PPL, 1.58 - 1.99 mm (1.82 ± 0.04, n=7), PEL, 1.56 - 1.91 mm (1.78 ± 0.04, n=7). Width, 1.36 - 1.62 mm (1.51 ± 0.03, n=7). Biometric data are given in Table 9.

Frontal lateral sides (Fig. 52D) convergent apically on basal half and strongly emarginate behind antennal sockets; anterior margin roundly arcuate. Margin of the frontal disk strongly carinate. Disk with five longitudinal costae; the median costa present on basal half; the lateral costae convergent apically through behind the antennal sockets and united with each other anteriorly; five cross costae present anteriorly between the lateral costa and the anterior marginal carina; the mediolateral costae shortly present on basal fourth. Surface of the disk sparsely furnished with minute spines.

Pronotal sides (Fig. 52A) feebly convergent forward on basal three-fourths, thence strongly convergent apically, and strongly carinate and densely furnished with minute spines. Anterior margin of pronotum broadly emarginate, the median portion nearly straight. Disk with six costae (Fig. 52E); the median four costae present on apical third and feebly elevated; the lateral costae strongly elevated, complete and interrupted at apical fourth; sides of these costae furnished with minute spines. Surface of the disk sparsely covered with coarse and round punctures which are separated by their own diameter to thrice the diameter and have minute setae in a trapezoid area on the mediobasal two-thirds; other area, except on costae, impunctate and shining.

Epipleura without stria, with a costa on margin of elytron, the costa sinuate at middle and furnished with minute spines on basal half; surface with two punctured rows, the punctures quadrate, large and shallow, the inner row complete and the outer (running close to the margin) shortly present on medio-apical fourth. Disk of elytron (Fig. 52A) with five spinal costae (excluding the costa on elytral margin); the 1st to 4th costae (naming from outside to inside) strongly elevated, complete and furnished with minute spine on their lateral sides; the sutural costa (closely present along suture) slightly elevated and furnished with minute spines only on the outer lateral side; interspace (Fig. 52F) between these costae with two punctured rows, the punctures round, large, deep and being separated by about their own diameter.

Propygidium short, depressed laterobasally and irregularly covered with coarse, round, shallow and spiral punctures, and intermingled with fine punctures among coarse ones; large, round and shallow punctures present along the anterior margin. Pygidium (Fig. 53D) irregularly covered with various sized and large punctures which are densely present medially, and other fine punctures intermingled.

Anterior margin of prosternal lobe (Fig. 52C, 53A) nearly straight; disk with a transverse punctured row on apical fifth, and sparsely with fine spines. Suture between the lobe and the keel clearly impressed. Prosternal keel feebly depressed, its carinal striae strongly elevated, convergent apically; posterior margin broadly and roundly emarginate. Lateral prosternal stria strongly carinate and divergent apically.

Anterior margin of mesosternum (Fig. 53A) sinuate, the median portion produced to fit the prosternal emargination; disk short and deeply excavate laterally (Fig. 53B); posterior margin angulate obtusely at middle; surface sparsely covered with fine spiral punctures, deeply excavate laterobasally and at apical third on lateral side, the laterobasal excavation becoming broader posteriorly and inwardly. Lateral metasternal stria carinate, extending posteriorly obliquely and angulate outwardly at basal fifth. Lateral disk with two deep excavations (Fig. 53C), the basal one present behind the mesocoxa and the apical one transverse and present on apical half; remains of the basal half covered with large round and shallow punctures.

Intercoxal disk of 1st abdominal sternum (Fig. 53C) short, with two excavations; the basal one deeply present on each lateral area, and the apical one shallowly on each latero-apical angles.

Protibia narrow, its outer margin with ten setae and angulate medially; interspace between apical 2nd and 3rd setae broad. Mesotibia with twelve setae on outer margin. Metatibia with thirteen setae on outer margin.

Male genitalia as shown in Fig. 54.

Specimens examined. [Honshû] <Nara-ken> 1 ex., Kasuga-yama, 8/i/1954, M. Ôtake leg. (NA); 3 exs., Ditto, 19/vi, 7, 14/vii/1957, T. Shibata leg. (NA); 2 exs., Ditto, 13/vi/1958, T. Nakane leg. (NA); 1 ex., 18/iv/1965, M. Gotô leg. (NA); 8 exs., Ditto, 26/xi/1958, T. Shibata leg. (NSMT); 1 ex., Nara, 28/iii/1959, no collector's name (NSMT).

Distribution. Japan (Honshû).

Remarks. Epiechinus arboreus is easy to be distinguished from other Japanese species of the subfamily Onthophilinae by its small size and the presence of minute spines on the dorsal surface in combination with the distinctly developed elytral costae.

Little is known about the habitats of this species. Lewis (1884) noted that this species was residing in galleries of wood-borers, probably Tomicus.

Table 9. Biometric data of Epiechinus arboreus (Lewis).

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APW 0.55-0.67 (0.62±0.01) 7

PPW 1.06-1.30 (1.21±0.03) 7

PL 0.59-0.71 (0.65±0.02) 7

EL 0.95-1.18 (1.10±0.03) 7

EW 1.36-1.62 (1.51±0.03) 7

ProW 0.51-0.67 (0.60±0.02) 7

ProL 0.16-0.26 (0.22±0.01) 7

PyL 0.39-0.47 (0.44±0.01) 7

PTL 0.47-0.63 (0.56±0.02) 7