Atholus bakeri (Bickhardt, 1914)

dela Cruz, Ian Niel & Ohara, Masahiro, 2023, Revision of the genus Atholus Thomson, 1859 (Coleoptera, Histeridae, Histerinae) from the Philippines with additional records, ZooKeys 1158, pp. 1-26 : 1

Atholus bakeri (Bickhardt, 1914)

Figs 6 , 54-57

Hister bakeri Bickhardt, 1914: 428 [Luzon Island].

Hister (Atholus) bakeri : Bickhardt 1917: 193 [catalogued].

Atholus bakeri : Bickhardt 1914: 428; Mazur 1984: 211; 1997: 129; 2011: 103 [catalogued].

Specimens examined.

1 syntype [ Luzon Island ] based on images, " Atholus bakeri n. sp. Bickh. / Los Banos, / P.I., Baker. / 1639" [sex undetermined, measurements not available] (MNHUB) .

Diagnosis.

This species has lateral pronotal striae interrupted in the anterolateral angle, and strong punctations on its entire pygidium. According to the original description of Bickhardt (1914), Atholus bakeri (Bickhardt, 1914) is most similar to A. torquatus (Marseul, 1854) except that the propygidium and pygidium of A. bakeri (Bickhardt, 1914) are strongly punctate. However, based on the syntype observed, the punctation is not as prominent as described and, in fact quite similar to that of A. torquatus (Marseul, 1854). The punctures are finer towards the apical end of the pygidium. Another distinguishable feature of A. bakeri (Bickhardt, 1914) is the medially straight frontal stria, while in A. torquatus (Marseul, 1854) it is weakly bent inwardly. However, several studied individuals of A. torquatus (Marseul, 1854) likewise seem to have their frontal stria medially straight.

Re-description.

Body (Fig. 6 ) oval, moderately convex and black; tibia and antenna rufous.

Head: clypeus (Figs 54 , 55 ) slightly crenate on anterolateral margin, apical margin slightly extended; frontal stria medially straight, complete, moderately impressed; eyes large, convex, clearly visible dorsally; mandibles with rounded outer margin curved inwardly; sub-apical tooth on left mandible large; mandibular apex acutely pointed.

Pronotum: marginal pronotal stria (Figs 54 , 55 ) laterally complete, continuous onto apical angle and crenate behind head; lateral pronotal stria moderately impressed, slightly crenate; apical end shortened and bent inwardly in a curved hook; lateral portion rather distant from margin; its basal end abbreviated from basal fifth of pronotal length.

Elytra: elytral epipleuron (Fig. 57 ) with few coarse punctures on apical half; marginal epipleural stria present on apical half; marginal elytral stria (Fig. 6 ) complete, slightly impressed; external and internal subhumeral striae absent; oblique humeral stria lightly impressed on basal third; dorsal elytral striae 1-4 complete; dorsal elytral stria 5 and sutural elytral stria present on apical half; disk with fine punctures.

Abdomen: propygidium (Fig. 56 ) moderately covered with coarse, round, and shallow punctures; interspaces with fine punctations; pygidial punctations similar to those of propygidium, becoming sparser apically.

Meso- and metaventrite: anterior margin of mesoventrite (Fig. 57 ) outwardly arcuate; marginal mesoventral stria crenate and complete; meso-metaventral suture clearly impressed, complete, medially angulate; punctations of intercoxal disk of metaventrite similar to those of mesoventrite; longitudinal suture of metaventrite lightly impressed; lateral disk of metaventrite moderately covered with large, round, shallow punctures.

Legs: posterior surface of protibia (Fig. 57 ) flattened and strongly dilated; outer lateral margin with four weak, almost inconspicuous teeth, topped by minute denticles.

Distribution.

Endemic to the Philippines ( Mazur 2011).

Biology.

Unknown.

Remarks.

The examined syntype of A. bakeri (Bickhardt, 1914) exhibits characters similar to a typical A. torquatus (Marseul, 1854). According to Desbordes (1917), A. torquatus (Marseul, 1854) and A. bakeri (Bickhardt, 1914) are very similar, being set apart by the pygidial punctation (strong in A. bakeri and apically finer in A. torquatus ). Although the only examined specimen of A. bakeri (Bickhardt, 1914) possesses similar pygidial punctations to A. torquatus (Bickhardt, 1914), this character remains the primary distinction until further examinations of other types is established. The authors would also encourage a comprehensive observation of both male and female genitalia for future works.

Figures

Figures 1 - 6. Philippine Atholus, dorsal habitus 1 A. philippinensis (Marseul, 1854) [IC- 21 - 18] 2 A. coelestis (Marseul, 1857) [IC- 21 - 20] 3 A. torquatus (Marseul, 1854) [IC- 21 - 49] 4 A. pirithous (Marseul, 1873) [IC- 21 - 47] 5 A. nitidissimus Desbordes, 1925 [syntype image] 6 A. bakeri (Bickhardt, 1914) [syntype image, No. 1639]. Scale bar: 1.00 mm.

Figures 54 - 57. Atholus bakeri (Bickhardt, 1914) 54 head and pronotum, dorsal view 55 head, frontal view 56 propygidium and pygidium 57 habitus, ventral view.