Atholus myrmidon ( Marseul, 1861 )

Cruz, Ian Niel dela, Hartini, Sri, Dwibadra, Dhian & Ôhara, Masahiro, 2024, Contribution to the Knowledge of the Genus Atholus (Coleoptera: Histeridae: Histerinae: Histerini) from the Indonesian Archipelago, Species Diversity 29 (1), pp. 119-139 : 127-131

Atholus myrmidon ( Marseul, 1861)

( Figs 1D , 6A–F , 7A–H , 8A–F , 12 )

Hister myrmidon Marseul, 1861: 542 (type locality: Sulawesi).

Atholus myrmidon : Lewis 1906: 402 (listed); Mazur 1984: 215; Mazur 1997: 131; Mazur 2011: 105 (New Guinea, Laos; catalogued).

Hister (Atholus) myrmidon : Bickhardt 1910: 54; Bickhardt 1917: 194 (catalogued); Desbordes 1917: 324 (keyed).

Specimen examined. OneJ. Sulawesi Island: Propinsi Sulawesi Selatan, Kabupaten Maros , near Makassar, 05.0108°S, 119.4038°E, 40 m a .s .l ., Cagar Alam Bantimurung , 27 October 2000, M . Ôhara leg . [SU-00-MO-002] [IC-22-in05] (1J SEHU).

Diagnosis. Atholus myrmidon is generally identified with combinations of uninterrupted lateral stria, elytral dorsal stria complete 1–4 complete, and fine to almost no punctation of pygidium. The paramere of aedeagus is stout and is moderately broad on the medio-apical portion.

Re-description. Male. Body length: PEL: 4.00 mm; APW: 1.52 mm; PPW: 3.00 mm; EL: 2.10 mm; EW: 3.40 mm. Body ( Figs 1D , 6A–C ) oval with wider posterior region, convex and black; tibia, antenna, mouthparts and apical elytral margin rufous.

Head. Anterior margin of clypeus entire, anterolateral margin sinuous; frontal stria ( Fig. 6D ) round, complete and deeply impressed; disk clothed with fine punctures, which are separated by two to three times their diameter, with alutaceous ground sculpture; occipital fovea absent; eyes large and convex, well-visible dorsally; labrum finely punctated, raised and transversely long, labral fringe absent; mandible covered with fine punctations, outer margin rounded and curved inwardly, sub-apical tooth on left mandible large, mandibular apex acutely pointed.

Pronotum. Pronotum bisinuously indented and feebly narrowed on anterior portion, with angles obtuse; marginal pronotal stria laterally complete, broadly interrupted behind head; lateral pronotal stria ( Fig. 6E ) deeply impressed and complete, the lateral portion rather distant from the margin, its basal end abbreviated to basal sixth of pronotal length; anterior pronotal stria present, connected to lateral stria; disk with sparse microscopic punctures, clothed with alutaceous microsculpture; area behind apical angle bare; posterior margin with row of few coarse punctures; ante-scutellar region with short, longitudinal puncture.

Elytra. Anterior margin with row of short, inconspicuous, longitudinal striae present on apical area around antero-scutellum; epipleural fossette almost no punctures on apical half; epipleural marginal stria present on apical third; elytral marginal stria complete and lightly impressed; external subhumeral stria ( Fig. 7B ) present medio-basally; internal subhumeral stria absent; oblique stria lightly impressed on basal third; dorsal striae ( Fig. 7A ) 1–4 complete; dorsal 5 and sutural striae present on apical half; the sutural stria longer towards the base; disk surface similar to pronotum with alutaceous microsculpture.

Propygidium and pygidium. Propygidium ( Fig. 7E, F ) moderately covered with coarse and round punctures, separated by 2–5 times their diameter, the puncture about 20 µm in diameter; interspace among the coarse punctures moderately covered with fine punctations; pygidium punctations ( Fig. 7E ) very sparse to almost no coarse punctures, the basal half with fine and sparse punctations, becoming finer on apex.

Prosternum. Prosternal lobe with round anterior margin ( Fig. 7C ), medio-apical end ascending; marginal stria deeply impressed, carinated and shortly interrupted at the middle, brief striae present on basolateral ends; lobe with moderate punctures on basolateral sides, separated by their own diameter, interspace among these punctures are sparse fine punctations, prosternal suture inconspicuous; prosternal process covered with sparse, fine punctures, the lateral sides descending; descending lateral stria deeply impressed and carinate, lateral disk with coarse punctations; basal half of process slightly narrow, posterior margin of basal lobe emarginated.

Meso- and metaventrite. Anterior margin arcuate outwards ( Fig. 7D ), marginal stria complete and moderately impressed, stria behind anterolateral angle present; disk sparsely clothed with fine punctures, which are separated by two to three times their diameter; meso-metaventral suture lightly impressed, complete and strongly angulated at middle; lateral metaventral stria ( Fig. 7D ) deeply impressed and carinated, extending obliquely and posteriorly, but not united with oblique stria which extends inwardly from basal third of metaventro-metepisternal suture; post-mesocoxal stria extending posteriorly and strongly curved along the posterior margin of mesocoxa, attaining the metaventro-mesepimeral suture; metaventrite with punctations of intercoxal disk similar to that of the apex of mesoventral plate; row of coarse punctures sometimes present along inside of basal portion of lateral stria; longitudinal suture lightly impressed; lateral disk of metaventrite densely covered with setiferous, large, round, shallow punctures; interspaces among the large punctures with sparse, fine punctations; mesepimeron and metepimeron covered with densely setiferous, large punctures; interspaces few, fine to coarse punctations; metepisternum with very sparse punctures on apical half; first abdominal sternite with punctation of intercoxal disk similar to that of metaventrite; surface of lateral disk similar to mesepimeron and metepimeron; lateral stria deeply impressed, slightly carinated and complete.

Legs. Anterior surface of protibia ( Fig. 7G ) flattened, moderately dilated and clothed with few, fine ocelloid punctures, the median area with weak strigate sculpture; outer lateral margin with three to four weak teeth topped by short denticles; anterior protibial stria complete and moderately impressed; inner marginal stria present on basal half; the inner apical margin with few sclerotized setae; posterior surface of protibia ( Fig. 7H ) covered with sparse, fine punctures, and strigate ground sculpture on outer basal surface, the outer region with few inconsistent ridges on surface; 10 denticles on both outer lateral margin and apical margin combined, one moderately larger on inner apical angle, 4 on outer sublateral margin; median posterior stria absent; inner posterior stria present on basal half, becoming carinate on apical half; row of sclerotized setae absent; row of setae on inner margin of protibia present on apical half, with row of setae follicles on basal half; protarsal groove shallow; profemur sparsely clothed with fine, ocelloid punctations, the surface with lightly strigate ground sculpture; marginal stria complete; anterior stria present on apical half; femoral stria almost complete; posterior margin with large and shallow punctations; row of short setae present on both basal and apical ends.

Male genitalia. Aedeagus ( Fig. 8A, B ) slightly stout, faintly curved ventrad on the apex; paramere about the same length as basal piece, moderately broad on medio-apical portion; median lobe moderately sclerotized, plumped on medio-apical end; eighth tergite ( Fig. 8E, F ) entire, with longitudinal fold on both lateral sides; ninth tergite ( Fig. 8C, D ) divided longitudinally, with lateral fold on both sides; tenth tergite simple. Spiculum gastrale almost as same length as ninth tergite, bifurcate on apical fifth.

Female genitalia. Not available.

Distribution. Indonesia: Greater Sunda (Sulawesi Island), New Guinea (Irian Jaya), and Laos ( Fig. 12 ).

Remark. Only a single male specimen was available for re-examination and re-description for this species.

Figures

Fig. 1. Some Indonesian Atholus, dorsal habitus. A, Atholus bifrons (Marseul, 1854), IC-22-in01; B, A. philippinensis (Marseul, 1854), IC- 22-in06; C, A. coelestis (Marseul, 1857), IC-22-in02; D, A. myrmidon (Marseul, 1861), IC-22-in05; E, A. famulus (Lewis, 1892), IC-22-in03; F, A. singalanus (Marseul, 1880), IC-22-in07; G, A. torquatus (Marseul, 1854), IC-22-in08. Scale bar: 1.00mm.

Fig. 6. Atholus myrmidon (Marseul, 1861), SEM micrographs, IC-22-in05. A, Habitus, dorsal view; B, ditto, ventral view; C, ditto, oblique view; D, head, dorsal view; E, pronotum; F, mouthparts, ventral view.

Fig. 7. Atholus myrmidon (Marseul, 1861), SEM micrographs, IC-22-in05. A, Elytra, dorsal view; B, ditto, oblique view; C, prosternal process; D, meso- and metaventrite; E, propygidium and pygidium; F, propygidium (punctation); G, protibia, dorsal view; H, ditto, ventral view.

Fig. 8. Atholus myrmidon (Marseul, 1861), male genitalia, IC-22-in05. A, Aedeagus, dorsal view; B, ditto, lateral view; C, ninth and tenth tergites, and spiculum gastrale, dorsal view; D, ditto, lateral view; E, eighth tergite and sternite, dorsal view; F, ditto, lateral view. Scale bar: 0.20mm.

Fig. 12. Map showing the occurrence of some species of Atholus from the Indonesian archipelago and its extra-limital distribution in the Oriental Region.