Stenotarsus nigricans Gorham

Arriaga-Varela, Emmanuel, Zaragoza-Caballero, Santiago, Tomaszewska, Wioletta & Navarrete-Heredia, Jose Luis, 2013, Preliminary review of the genus Stenotarsus Perty (Coleoptera: Endomychidae) from México, Guatemala and Belize, with descriptions of twelve new species, Zootaxa 3645 (1), pp. 1-79 : 32-33

Stenotarsus nigricans Gorham

( Figs. 30 , 45 , 68 , 103 , 137, 142 , 172 , 191 , 226 –227, 253 , 261 )

Stenotarsus nigricans Gorham, 1890: 135 . Blackwelder 1945: 440; Strohecker 1953: 54; Shockley et al. 2009a: 83.

Diagnosis. This species superficially resemble the uniformly brown specimens of S. militaris Gerstaecker , but can be readily distinguished by the shape of the median lobe ( Figs. 226–227 ), which is comparatively stouter and not constricted apically, in lateral view, and by the apex of the ventrite V of female, which is at most weakly emarginate ( Figs. 45 , 191 ), instead of strongly emarginate as in S. militaris .

Description of males. Body 5.1–5.9 mm long, large short oval, convex ( Fig. 30 ), 1.60–1.65X as long as width, 2.87–3.18X as long as wide. Uniformly ferruginous red or dark brown, except antennomeres 8–11 which are black, antennomeres 6–7 infuscate. Densely covered with long, suberect, light coppery setae.

Head: Clypeus transverse, 2.2X wider than long. Terminal labial palpomere narrow, acuminate, narrowly truncate apically. Interocular distance 0.65–0.69X as wide as head. Antenna moderately long and slender ( Fig. 68 ), 0.41–0.42X as long as body; scape 1.5X as long as wide, 1.9X longer than pedicel; pedicel as long as wide; third antennomere 1.9X as long as wide, 1.7X as long as the pedicel; fourth 1.7X as long as wide, 1.6X as long as pedicel; fifth to seventh subequal to fourth; eighth 1.3X as long as wide, 1.6X longer than the pedicel; antennal club 0.39X as long as the total antennal length, with segments slightly asymmetrical; ninth antennomere weakly widened apically, as long as wide, 2.3X as long as pedicel; tenth widened apically, 0.9X as long as wide, 2.2X as long as pedicel; terminal antennomere asymmetrical, subrectangular, 1.4X as long as wide, 3.7X as long as pedicel.

Prothorax: Pronotum widest at base, transverse ( Fig. 103 ), 2.0–2.2X wider than long, 1.82–1.89X wider at base than at front angles, 2.22–2.26X wider than head. Sides almost continuously rounded, less convergent in basal half. Front angles produced, right-angled or briefly obtuse, briefly rounded at tip. Hind angles right-angled. Anterior margin narrow, distinctly arcuate medially. Lateral margins distinctly raised; markedly wide, weakly narrowing posteriorly, more strongly near base; width of margin at base1/4 of the distance between basal pore and hind angle; area between marginal line and pronotal edge flat to weakly concave. Disc moderately convex, finely and closely punctate. Longitudinal sulci moderately deep, lacking anteriorly, short, weakly curved medially. Basal pores large, slightly curved, oblique. Basal sulcus complete, slightly feeble near scutellum. Pronotal base lobed medially. Prosternal process moderately wide at base, slightly widened posteriorly; as wide as longitudinal procoxal diameter apically.

Pterothorax: Scutellum triangular, moderately large, 1.77–1.86X wider than long, 0.17–0.18X as wide as pronotum. Elytra 3.4–3.6 mm long; 1.11–1.16X longer than wide, 3.32–3.54X longer and 1.38–1.48X wider than pronotum; long ovoid, widest before basal third, weakly convergent in medial half, then roundly convergent to the moderately acuminate apex. Densely punctate with foveolate punctures moderately large and deep, separated by 1.5–3.0 diameters, sparser and shallower apically and near scutellum. Humerus moderately prominent. Epipleuron at base 0.85X as wide as the intercoxal process of metaventrite. Mesoventrite deeply excavated in front; bearing small setose pores laterally ( Fig. 137 ); mesoventral process slightly wider than longitudinal coxal diameter, without medial carinae. Metaventrite weakly convex, without modifications on the anterior margin; with pair of small setose pores of approximately same diameter posterior to each mesocoxa ( Fig. 142 ). Metepisternum with small setose pore.

Legs: moderately long and slender ( Fig. 172 ). Trochanters simple. Meso- and metafemora moderately widened at midlength, unarmed; metafemur as long as mesofemur, bearing moderately long decumbent setae. Meso- and metatibiae moderately slender; metatibia as long as metafemur, 0.32–0.33X as long as elytra, gradually widened distally, linear, unarmed. Metatarsus 0.52–0.58X as long as metatibia; second tarsomere 2.5X as wide apically as fourth tarsomere at midlength.

Abdomen: ventrite I slightly shorter than metaventrite and ventrites II–V combined, with moderately coarse foveolate punctation, without protuberances. Ventrite V slightly longer than IV, with apex truncate. Ventrite VI rounded apically. Tergite VIII slightly truncate. Median lobe slender, curved, subequal in width along most of its length, tapering apically, in ventral view ( Fig. 227 ), slightly sinuate, in lateral view ( Fig. 226 ). Tegmen with moderately large submembranous tegminal plate.

Description of females. Body 5.4–5.9 mm long, 1.75–1.85X as long as wide, 2.9–3.2X as long as high. Antenna 0.38X as long as body. Pronotum 2.15–2.20X wider than long, 1.90–1.95X wider at base than at front angles, 2.25X wider than head. Elytra 3.60–4.05 mm long, 1.19–1.25X longer than wide, 3.72–3.87X longer and 1.38–1.45X wider than pronotum. Metatibia 0.28–0.29X as long as elytra. Metatarsus 0.53–0.55X as long as metatibia. Abdomen with ventrite truncate. Ovipositor with proctiger rounded, coxites moderately wide, without styli ( Fig. 253 ).

Sexual dimorphism. Females have shorter antennae and longer, and wider elytra.

Variation. The Guatemalan holotype is considerably darker than the Mexican specimens.

Material examined. Type. Holotype (female): Holotype [round, red bordered label] / type [round, orange bordered label] / Teleman, Guatemala, G.C. Champion / Sten. nigricans Gorham [h] / B.C.A., Col., VII, Stenotarsus [p] nigricans Gorh. [h] (NHM).

Other material. MÉXICO: Jalisco, Casimiro Castillo, Arroyo Tacubaya, BTS, 600m, ex Rigidoporus microsporus , 4.VII.2002, 19º35’47’’N, 104º25’52’’W, H. E. Fierros-López col. (2 males, 11 females: CZUG); MÉXICO: Jalisco, Casimiro Castillo, Arroyo Tacubaya, BTS, 600m, ex Rigidoporus microsporus , 4.VII.2002, 19º35’47’’N, 104º25’52’’W, H.E. Fierros, A. Rocha & G. González cols. (2 males, 1 female: CZUG); C. de Plumas 15 / Mexico, Coll. J. Flohr / Stenotarsus sp. indesct., det. H.F. Strohecker (1 male: MNB).

Distribution. GUATEMALA: Alta Verapaz; MEXICO: Jalisco ( Fig. 261 ).

Biological Notes. Altitudinal range: 600 m. Habitat: tropical subdeciduous forest. Period of activity: July. Host fungi: Rigidoporus microsporus ( Polyporales : Meripilaceae ).

Remarks. Since the holotype is a female, the identity of the Mexican specimens cannot be stated with total certainty. However, they fit quite well in all characters, except for the lighter color. The alleged relation suggested by Gorham (1890) of this species to the Colombian species S. rubicundus Gerstaecker and S. sericatus Gerstaecker , is artificial, based solely on its dark fuscous color.

This species is recorded from México for the first time. A specimen in MNB is labeled as collected on “C. de Plumas”. That locality was not identified unambiguously. It could refer to “ Cerro de las Plumas (Ihuitepec)” in Santa María Teopoxco, Oaxaca, or as stated by Selander & Vaurie (1962: 25) could be a misspelling of “Cerro de las Palmas” Veracruz. However, “Cerro de las Palmas” was not located with certainty by Selander & Vaurie (1962).

Figures

FIGURES 26 – 37. Habitus in dorsal view of Stenotarsus spp. Scale bar = 1 mm. 26 – 27) S. militaris; 28) S. molgorae; 29) S. monterrosoi; 30) S. nigricans; 31 – 32) S. oblongulus; 33) S. ovalis; 34) S. parallelicornis; 35) S. raramurii: 36) S. rubrocinctus; 37) S. rulfoi.

FIGURES 43 – 49. 43 – 47. Habitus in ventral view of Stenotarsus spp. 48 – 49 Habitus in lateral view of Stenotarsus spp. 43) S. guatemalae; 44) S. kafkai; 45) S. nigricans; 46) S. militaris; 47) S. thoracicus; 48) S. incisus; 49) S. oblongulus.

FIGURES 54 – 71. Right antennae of Stenotarsus spp. 54) S. cortesi; 55) S. exiguus; 56) S. globosus, S. rubrocinctus; 57) S. guatemalae; 58) S. incisus; 59) S. kafkai; 60) S. latipes; 61) S. lemniscatus; 62) S. marginalis; 63) S. mesoamericanus; 64) S. mexicanus; 65) S. militaris; 66) S. molgorae; 67) S. monterrosoi; 68) S. nigricans; 69) S. oblongulus; 70) S. ovalis; 71) S. parallelicornis.

FIGURES 90 – 104. Pronotum of Stenotarsus spp. 90) S. cortesi; 91) S. exiguus; 92) S. globosus; 93) S. guatemalae; 94) S. incisus; 95) S. kafkai; 96) S. latipes, S. molgorae; 97) S. lemniscatus; 98) S. marginalis; 99) S. mesoamericanus; 100) S. mexicanus; 101) S. militaris; 102) S. monterrosoi; 103) S. nigricans; 104) S. oblongulus.

FIGURES 126 – 143. Thoracic structures of Stenotarsus spp. 126 – 133. Prosternal process. 134 – 136. Scutellum. 137 – 138. Mesoventrite. 139 – 140. Metepisternum. 141 – 143. Anterolateral part of metaventrite. 126) S. cortesi; 127) S. globosus, S. rubrocinctus; 128) S. meosamericanus; 129) S. oblongulus; 130) S. ovalis; 131) S. shockleyi; 132) S. spiropenis; 133) S. thoracicus; 134) S. globosus; 135) S. ovalis; 136) S. spiropenis; 137) S. nigricans; 138) S. spiropenis; 139) S. ovalis; 140) S. spiropenis; 141) S. marginalis; 142) S. nigricans; 143) S. spiropenis. PC. Procoxal cavity. PR. Procoxal rest. SP. Setose pore. MC. Mesocoxal cavity.

FIGURES 158 – 173. Hind legs of male Stenotarsus spp. 158) S. cortesi; 159) S. exiguus; 160) S. globosus; 161) S. guatemalae; 162) S. incisus; 163) S. kafkai; 164) S. latipes; 165) S. lemniscatus; 166) S. marginalis; 167) S. mesoamericanus; 168) S. mexicanus; 169) S. militaris; 170) S. molgorae; 171) S. monterrosoi; 172) S. nigricans; 173) S. oblongulus.

FIGURES 186 – 195. Abdmonal structures of Stenotarsus spp. 186. Lateral view of abdomen of male S. sallaei. 187 – 191. Abdomen of female Stenotarsus spp. 192 – 195. Tergite VIII of female Stenotarsus spp. 187) S. globosus; 188) S. incisus; 189) S. militaris; 190) S. monterrosoi; 191) S. nigricans; 192) S. lemniscatus; 193) S. monterrosoi; 194) S. militaris; 195) S. nigricans.

FIGURES 224 – 243. Lateral and ventral view of median lobe of edeagus of Stenotarsus spp. 224 – 225) S. monterrosoi; 226 – 227) S. nigricans; 228 – 229) S. oblongulus; 230 – 231) S. ovalis; 232 – 233) S. parallelicornis; 234 – 235) S. rulfoi; 236 – 237) S. sallaei; 238 – 239) S. smithi; 240 – 241) S. spiropenis; 242 – 243) S. thoracicus.

FIGURES 244 – 256. Female genitalia structures of Stenotarsus spp. 244) Ovipositor with spermatheca and accessory gland of S. spiropenis, dorsal. 245 – 256. terminal part of ovipositor, dorsal. 245) S. cortesi; 246) S. exiguus; 247) S. globosus, S. raramuri, S. rubrocinctus, S. shockleyi; 248) S. incisus; 249) S. latipes; 250) S. mesoamericanus; 251) S. mexicanus; 252) S. monterrosoi; 253. S. nigricans. 254. S. ovalis. 255. S. sallaei. 256. S. thoracicus.

FIGURES 260 – 262. Distributional maps of Stenotarsus spp. 260) S. guatemalae (C), S. marginalis (S); 261) S. kafkai (C), S. mexicanus (S), S. nigricans (T); 262) S. latipes (C), S. shockleyi (S). Yellow circles (C), red squares (S), blue triangles (T).