Hister pygmaeus: DeGeer, 1774: 344, corrected by Hoffmann, 1803: 87.
Hister nanus Scriba, 1790: 73. nec. Piller et Mitterpacher, 1783, synonymized by Hoffmann, 1803: 87.
Hister rotundatus Kugelann, 1792: 304.
Hister punctatus: Thungerg, 1794: 64, corrected by Hoffman, 1803: 87.
Hister quadristriatus Thunberg, 1794: 65, synonymized by Kanaar, 1980: 63, also by Dahlgren, 1980: 46.
Hister piceus Marsham, 1802: 97, synonymized by Stephens, 1830: 157.
Hister rotundatus var. "b" Hoffmann, 1807: 42, synonymized by Erichson, 1834: 175.
Saprinus rotundatus: Erichson, 1834: 175.
Saprinus deletus J. E. LeConte, 1844: 186, synonymized by J. L. LeConte, 1861: 77.
Dendrophilus (sic!) rotundatus var. quinquestriatus: Dejean, 1837: 143 (nom. nud.).
Gnathoncus punctulatus Thomson, 1862: 242, synonymized by Reitter, 1896: 306.
Saprinus ignobilis Wollaston, 1864: 173, synonymized by Schmidt, 1895: 177.
Saprinus wollastoni Marseul, 1864b: 353 (emend.)
Tribalus (sic!) quadristriatus Wollaston, 1869: 310, synonymized by Lewis, 1886b: 280.
Saprinus rotundatus var. communis: Horn, 1873: 315.
Saprinus (Gnathoncus) routundatus: Marseul, 1873: 221 [New to Japan].
Gnathoncus communis: Schmidt, 1884: 160.
Gnathoncus rotundatus var. punctulatus: Reitter, 1896: 306.
Gnathoncus nanus: Reichardt, 1941: 191; Mazur, 1973: 27; Kryzhanovskij and Reichardt, 1976: 116; Vienna, 1980: 120; Hisamatsu, 1985: 222.
Gnathoncus rotundatus var. subsuturalis Reitter, 1896: 307.
Gnathoncus punctulatus var. pygidialis Ganglbauer, 1899: 380.
Gnathoncus punctulatus var. subsuturalis: Reitter, 1906: 266.
Gnathoncus rotundatus: Jacquelin-Duval, 1858: 112; Mazur, 1980: 88; 1984: 105.
Japanese name: Maru-mame-emma-mushi.
Gnathoncus rotundatus: Ôhara, 1994, 220.
Description. Body length, PPL, 1.91 - 2.45 mm (2.15 ± 0.04, n=17), PEL, 1.84 - 2.35 mm (2.05 ± 0.04, n=17). Width, 1.42 - 1.76 mm (1.58 ± 0.02, n=17). Biometric data are given in Table 43. Body broadly oval and feebly depressed medially. Cuticles shining and black; antennae, mandible, tibiae dark rufopiceous, and club of antennae rufotestaceous.
Front sparsely covered with deep and moderate punctures, interspace among the punctures sparsely clothed with fine punctures.
Pronotal sides (Fig. 126B) feebly arcuate and convergent on basal three-fourths, thence strongly convergent to apices. Apical angles obtuse. Marginal stria feebly carinate and complete. Disk sparsely and evenly covered with coarse, round and deep punctures, which become coarser on the basal half; interspace among the punctures sparsely and finely punctate. Antiscutellar area feebly depressed and coarsely and somewhat densely punctate.
Epipleura of elytra not concave. Marginal epipleural stria finely and clearly impressed and complete. Another epipleural stria complete, carinate and clearly impressed between marginal epipleural and elytral striae. Marginal elytral stria complete and carinate, its basal end inwardly bent, and apical end extending across elytral apex to medio-apical angle of elytra, then a little extending apically. Surface of epipleura and marginal elytral striae densely with a row of coarse punctures. Internal subhumeral stria rudimentary on basal third and usually crossed by a number of fine, oblique rugae. First dorsal stria (Fig. 126B) deeply impressed on basal three-fourths. Second to 4th dorsal striae deeply impressed, crenate and present on basal half, but usually a little extending beyond the half. Fifth stria represented only by a short, curved, transverse line at base. Sutural stria usually present on basal fourth, sometimes shorter than basal sixth. Surface of apical half to two-thirds of elytra covered with longitudinal, oblong, deep punctures, which are about as coarse as those of the extreme base of the pronotum and separated by two to three times their diameter; surface of basal half to one-third finely and sparsely punctate, the punctures being separated by four to seven times their diameter; apical transverse region (around apical stria) densely and longitudinally rugate; extreme apex of elytra impunctate. Interspace among discal elytral punctures smooth and rarely microscopically punctate.
Propygidium densely covered with coarse and transverse oblong punctures on apical half, which are as large as those occuring posterior to apical elytral stria, and more finely and sparsely punctate on basal half. Interspace among the punctures with lightly impressed, fine and irregularly transverse lines, these lines being heavily impressed on basal half. Pygidium coarsely and densely covered with transverse oblong punctures, the punctures being separated by their longer diameter to twice the diameter and their posterior margin usually emarginate; on apex those punctures are much finer.
Anterior margin of median portion of prosternum (Fig. 127B) round. Ventral disk of keel even, broad and sparsely and finely punctate; the punctures being separated by about three to seven times their diameter; ground surface densely covered with microscopic and longitudinal rugae except medially. Carinal stria complete, carinate and sinuate. Keel without preapical fovea. Descending lateral stria short and present on median third of prosternum, its apical end attaining to medio-apical third of keel.
Anterior margin of mesosternum feebly bisinuate with a slight projection. Marginal stria of mesosternum strongly carinate and complete. Disk sparsely covered with moderate and round punctures which are separated by four to six times their diameter; interspace among the punctures sparsely and finely punctate. Meso-metasternal suture strongly impressed and densely crenate, usually the lateral sixth reduced. Intercoxal disk of metasternum sparsely clothed with fine punctures which are separated by five to ten times their diameter and become coarser in the lateral and posterior areas along the marginal suture or lateral stria. Lateral metasternal stria carinate and deeply impressed on lateral three-fourths of the intercoxal disk. Lateral disk densely covered with large, round and setiferous punctures, which become denser posteriorly. Metepisternum more densely covered with large punctures than on lateral disk.
Intercoxal disk of 1st abdominal sternum almost completely striate, the stria not attaining the posterior margin, deeply impressed and carinate. Surface of disk evenly covered with coarse longitudinal oblong and deep punctures; interspace among the punctures sparsely clothed with microscopic punctures.
Protibia (Fig. 126E) with 8 denticles on outer margin, the interspace between the apical 3th and 4th denticles strongly emarginate.
Table 43. Biometric data of Gnathoncus rotundatus (Kugelann).
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APW 0.51-0.74 (0.63± 0.01) 17
PPW 1.23-1.52 (1.36± 0.02) 17
PL 0.64-0.83 (0.75± 0.01) 17
EL 1.15-1.42 (1.30± 0.02) 17
EW 1.42-1.76 (1.58± 0.02) 17
ProW 0.78-0.98 (0.90± 0.01) 17
ProL 0.15-0.25 (0.19± 0.01) 17
PyL 0.74-0.88 (0.79± 0.01) 17
PTL 0.49-0.56 (0.53±0.005) 17
MSTL 0.54-0.64 (0.59± 0.01) 17
MTTL 0.61-0.76 (0.69± 0.01) 17
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Male genitalia as shown in Fig. 129.
Ohara (1994: Fig. 129)
Remarks. Gnathoncus rotundatus is quite similar to G. communis in all external characters examined, and the differences are very subtle; the shape of the protibia and the male genitalia should be used to distinguish these two species positively.
Gnathoncus rotundatus is coprophile and known from a wide range
of habitats. Mazur (1981) recoded this species from the nests
of the following birds and animals: owl, Strix L.; hoope, Upupa
epops L.; hooded-crow, Corvus corone cornix L.; starling, Sturnus
vulgaris L.; squirrel, Sciurus vulgaris L.; rabbit, Oryctolagus
cuniculus (L.), and humster, Cricetus cricetus (L.).
Specimens examined. 16 exs., Shimohoro, collected from breeding fox dung; 1 ex., Kushiro Zoo, collected from animal dung.
[Hokkaidô] 1 ex., Futatsu-yama, Shibecha, Kushiro, 16/v/1986, K. Ijima leg. (IJ); 10 exs., Shimohoro, Tsurui, Kushiro moor, 1/vi/1992, M. Ôhara leg.; 9 exs., Ditto, 9/vi/1992, M. Ôhara leg.; 1 ex., Kushiro Zoo, Yamahana, Kushiro, 9/vi/1992, M. Ôhara leg.
[Honshû] <Ôsaka-fu> 1 ex., Nishinari, 15/v/1950, K. Sawada leg. (NA).
Distribution (Fig. 131). Japan (Hokkaidô, Honshû); nearly whole Holarctic region, Taiwan, South Africa.
[Honshû] Aomori-ken: Hiraka-machi (2 exs., 21/v/1972, APM), A. Satoh; Kuroishi-shi (1 ex., 20/v/1972, APM), A. Satoh.
