Gnathoncus communis (Marseul, 1862)

Saprinus communis Marseul, 1862: 501, synonymized with Gnathoncus rotundatus by Horn, 1873: 314, but revived by Mazur, 1990: 744.

Gnathoncus communis: Mazur, 1990, 744 [Australia]

Gnathoncus schmidti Reitter, 1894: 239; Stockmann, 1957: 75, fig. 4, 9, 14, 19, 24; Halstead, 1963: 13, fig. 27, 27b-d; Vienna, 1980: 123, fig. 45c, i, 46c, synonymized by Mazur, 1990: 744.

Gnathoncus nidicola Joy, 1907: 133, tab., V, fig. 2; Auzat, 1917: 208; Reclaire en van der Wiel, 1936: 208, synonymized by Stockmann: 73.

Gnathoncus nidicola var. auzati Pic, 1918: 9.

Gnathoncus punctor: Reichardt, 1941: 164, fig. 75A, 77B; Hinton, 1945: 326, fig. 32, 34, 36, 41, 42, 45 [male genitalia], corrected by Stockmann: 73.

Gnathoncus idiopygus Casey, 1916: 255, synonymized by Mazur, 1990: 744.

Japanese name: Nise-maru-mame-emma-mushi.

Original description. "Ovale, assez, brun luisant. Antennes rousses. Front convexe, arrondi, dessément et également pointillé, non séparé de l'épistome, entouré par derrière d'une fine strie qui s'évanouit au níveau des yeux. Pronotum beaucoup plus large que long, anvecé en angle obtus au milieu de la base, arrondi sur les côtés, fortement rétréci et échancré en devant, avec les angles abaissés et arrondis, convexe, couvert d'une ponctuation assez serrée, rugueuse et plus forte latéralement; strie marginale entière. Écusson en très petit triangle allongé. Élytres presque deux fois plus longues que le pronotum, de sa largeur à la base, dilatées en arc sur les côtés, rétrécies et coupées droit au bout avec les angles arrondis, relevées légèrement sur la suture à leur partie postérieure, couvertes d'une ponctuation forte assez écartée, mais serrée et rugueuse sur leur tiers postérieur; stries fortes, densément ponctuées, 1-4 dorsales parallèles, cependant rapprochées par paires par derrière, première atteignant presque le bout, mais d'une manière confuse; deuxième et quatrième raccourcies plus tôt et églaes à peu près entre elles, troisième un tant soit peu plus longue, cinquième réduite à un tout petie arc basal; suturale courte basale; humérale bien marquée, parallèle à la premiére dorsal; subhumérale interne disjointe, longue; extrene courte, à peine séparée du sillon latéral qui se continue le long du bord apical jusqu'à la suture; bord infléchi bisillonné, ponctué dans l'intervalle des sillons. Propygidium incliné, court, transverse, densément et également pointillé. Pygidium ponctué de même, entièrement rabattu, légèrement convexe. Prosternum plan, accuminé en devant, étranglé au niveau des fossettes antennaires, avec quelques points; stries fortes se joignant en angle fort aigu. Mèsosternum entièrement rebordé, parsemé de points assez forts, distinctement séparé du métasternum qui est ponctué comme lui. Pattes rousses; jambes antérieures dilatées, garnies de cinq à six denticules séparés en deux groupes; intermédiaires aussi larges, et postérieures plus étroites, avec quelques cils courts.

Cette espèce, que je tiens de M Asa Fitch, a beaucoup de rapports ave le S. routundatus; elle s'en distingue par sa ponctuation beaucoup plus forte et plus serré, et par la disposition des stries des élytres. Elle a été trouvée près d'Albany, aux États-Unis."

Ohara (1994)

Description. Body length, PPL, 2.21 - 2.57 mm (2.34 ± 0.04, n=10), PEL, 2.01 - 2.40 mm (2.19 ± 0.03, n=10). Width, 1.47 - 1.89 mm (1.69 ± 0.04, n=10). Biometric data are given in Table 44. Body broadly oval and strongly convex. Cuticles shining and black, but a few specimens very dark rufopiceous; antennae dark rufopiceous with club rufotestaceous; legs dark reddish brown.

Front of head sparsely with fine and transverse punctures, and with round punctures posteriorly.

Pronotal sides (Fig. 126C) feebly arcuate and convergent on basal two-thirds, thence feebly convergent to apices. Apical angles obtuse. Marginal stria carinate and complete, its anterior portion weakly carinate and indistinct. Middle of disk finely punctate, the punctures being separated by three to five times their diameter; towards sides the punctures become coarser and denser; base sparsely and coarsely punctate, the punctures being nearly as coarse as those of sides. Interspace among punctures smoother and with occasional microscopic punctures.

Epipleura of elytra not concave. Marginal epipleural stria finely impressed and complete. Another epipleural stria complete and subcarinate between the marginal epipleural and elytral striae. Marginal elytral stria complete and carinate; its apical end extending across elytral apex to medio-apical angles of elytra and then a little extending basally. Surface between marginal epipleural and another epipleural striae with 2 rows of longitudinal-oblong and coarse punctures. Subhumeral stria present on median third. Oblique humeral stria (Fig. 126C) present on basal third, and usually crossed by a number of fine, oblique rugae so that it appears to be irregular. First and 3rd dorsal striae deeply impressed on basal two-thirds and carinate. Second and 4th dorsal striae a little shorter than the 3rd. Fifth and sutural striae only represented by a short, curved, transverse line at base. Surface of apical half of elytra covered with coarse, oval punctures which are about as coarse as those of the extreme base of the pronotum and separated by their own diameter to twice the diameter; surface of basal half slightly more finely and distinctly more separately punctate than middle of pronotal disk; extreme apex of elytra (around apical stria) impunctate. Interspace among all discal elytral punctures smooth or nearly so.

Propygidium densely covered with coarse, round punctures on apical half which are as large as those occurring anteriorly to apical elytral stria and finely and sparsely punctate on basal half. Interspace among punctures on basal half with lightly impressed, fine and irregularly transverse lines. Pygidium densely and coarsely covered with transverse-oblong and umbilicate punctures, which become denser apically and round on the mediobasal region.

Anterior margin of median portion of prosternum (Fig. 127C) round. Ventral disk of keel even, sparsely covered with moderate and longitudinal-oblong punctures. Carinal striae complete, strongly carinate and sinuate, the anterior ends united with each other in an arch. Preapical fovea absent. Descending lateral stria shortly present on median third, its apical end attaining to apical third of keel.

Anterior margin of mesosternum bisinuate with a feebe median projection. Marginal stria of mesosternum complete and subcarinate. Disk sparsely covered with large and round punctures, which are separated by two to three times their diameter. Meso-metasternal suture slightly impressed and accompanied by a coarsely and sparsely crenate line. Median area of intercoxal disk finely punctate, the punctures being separated by three to four times their diameter; lateral and posterior fourth sparsely covered with large, round and setiferous punctures, these being a little larger than those of mesosternal disk; interspace among large punctures sparsely clothed with fine punctures. Lateral metasternal stria strongly carinate, extending obliquely and posteriorly, and usually present on basal two-thirds. Lateral disk densely covered with large, round and setiferous punctures, which are somewhat larger than those of the intercoxal disk. Metepisternum densely punctate, the punctures being as large as those of lateral disk.

Intercoxal disk of 1st abdominal sternum completely striate. Surface of disk sparsely and finely punctate on median area, and coarsely punctate laterally, the punctures on lateral areas being smaller than the punctures of mesosternal disk.

Protibia (Fig. 126F) with 7 spinules on outer margin, the apical-outer angles bearing large 3 spinules, and only feebly emarginate between spinules.

Table 44. Biometeric data of Gnathoncus communis (Marseul).

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APW 0.64-0.88 (0.72±0.02) 10

PPW 1.35-1.62 (1.49±0.02) 10

PL 0.74-0.91 (0.80±0.02) 10

EL 1.23-1.64 (1.36±0.04) 10

EW 1.47-1.89 (1.69±0.04) 20

ProW 0.81-1.05 (0.94±0.02) 10

ProL 0.15-0.25 (0.20±0.01) 10

PyL 0.64-0.93 (0.78±0.03) 10

PTL 0.47-0.64 (0.54±0.02) 10

MSTL 0.54-0.69 (0.61±0.01) 10

MTTL 0.66-0.78 (0.73±0.01) 10

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Male genitalia as shown in Fig. 130.

Ohara (1994: Fig. 130)

Remarks. Gnathoncus communis is quite similar to G. rotundatus in all external characters, but the two species can positively be distinguished by the shape of the protibia and the male genitalia.

Little is known about the habitat of this species in Japan. Mazur (1981) reorded G. communis in the nests of the following birds: carrion crow, Corvus corax L.; jackdaw, Corvus monedula (L.); tawny owl, Strix aluco L. and goshawk, Accipiter gentilis (L.).

Ohara (1994)

[Honshû] <Tôkyô-to> 10 exs., Setagaya, 18/ix/1949, Ôhira leg. (NA).

[Kyûshû] <Kagoshima-ken> 1Åâ, Uenosono, Kagoshima, 2/xi/1982, T. & T. Nakane leg. (NA).

Distribution. Japan (Honshû, Kyûshû); North America; Eurupa; Caucasus; Central Asia; Sakhalin; Egypt; Australia.


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