Diochus angustiformis, Irmler, 2017

Irmler, Ulrich, 2017, A review of the Neotropical genus Diochus ERICHSON, 1840 (Coleoptera: Staphylinidae: Staphylininae), Beiträge Zur Entomologie = Contributions to Entomology 67 (1), pp. 1-62 : 26-27

Diochus angustiformis spec. nov.

urn:lsid:zoobank.org:act:BB731197-AF1B-458F-AE6B-BC32865D30C9

Figs 28A–C , 39L , 44C

Type material: male, Holotype: Costa Rica: S Rincon de la Vieja, Rd. Hacienda Guachipilin > Santa Maria (10°42.43'–45.10'N, 85°20.15'–22.45'W), 520–700 m elevation, car net, farmland & dry forest, 4.12.2012, leg. Schülke & Grünberg ( MSC).

Paratypes: Mexico: Chiapas, Pozas, de Berriozabal, ca. 5 km W Tuxtla , 750 m elevation, leaf litter at base of escarpment along stream, 2 males, 4 females, 3.6.1991, leg. J. Ashe, #53 ( KNHM) ; Chiapas, Cinco Cerros , 5 km S Rizo de Oro, sifted leaf litter in dry stream bed, 810 m elevation, female, 8.6.1991, leg. J. Ashe #78 ( KNHM) ; Chiapas, El Chorreadero, 8 km SE Chiapa de Corzo, sifted leaf litter, 650 m elevation, female, 3.6.1991, leg. J. Ashe #56 ( KNHM) ; Just E Acala , SE of Tuxtla Gutierrez (16°38'N, 92°48'W), rocky edge of large stream in shade, 3200 ft., 1 male, 1 female, 2.1.1973, lg. H. Frania ( AMNH) ; Chiapas, 12 mi NW Ocozocautla, 3200 ft. elev., Berlese , litter oak-tropical evergreen forest, 3 males, 2 female, 4.9.1973, leg. A. Newton ( FMNH) ; Chiapas, El Chorreodero, NE Tuxtla Gutz, 730 m elev., sifting, tropical deciduous litter along stream, female, 5.5.1977, leg. J.S. Ashe ( FMNH) ; Jalisco, Puerto Los Mazos, 10 mi SW Autlán, 4400 ft elev., Berlese , litter oaktropical decid. forest, male, 25.9.1973, leg. A. Newton ( FMNH) ; S.L. Potosi, 3 mi W El Naranjo , sifting, leaf litter, female, 1.– 18.6.1971, leg. A. Newton ( FMNH) ; Oaxaca, 7.3.mi N Chacalpa, Hwy 75 (96°28'W, 15°49'N), 410 m elev., tropical deciduos forest, sfting, leaf litter, 29.4.1977, leg. J.S. Ashe ( FMNH) ; Belize: Orange Walk District, Rio Bravo Conserv. Area, pond at end Orchard trail (17°50.48'N, 89°02.43'W), water edge litter, 1 male, 2 females, 28.4.1996, leg. C. Carlton (2 KNHM, 1 UIC) ; same region, but Rd to Archaeological site (17°50.27'N, 89°01.8'W), 3 females, 25.4.1996, leg. C. Carlton, #036 (2 KNHM, 1 UIC) ; same location, but (17°50.33'N, 89°01,28'W), collected by flight intercept trap, 2 females, 18.– 25.4.1996, leg. C. Carlton & V. Mosley, #026 ( KNHM) ; same location, but Archaeological camp. (17°50.28'N, 89°01.09'W), collected by berlese, female, 4.4.1996, leg. C. Carlton, #091 ( KNHM) ; same region, Rio Bravo Conserv. Area, La Milpa (19°50.23'N, 89°01.06'W), UV light, female, 1.5.1996, leg. C. Carlton, V. Moseley #077 ( KNHM) ; Guatemala: Zacapa, 7.6 km W Teculatán , 330 m elevation, along stream in leaf packs, male, 26.6.1993, leg. J. Ashe & R. Brooks, #03-108 ( KNHM) ; Nicaragua: Rio San Juan Dept., 60 km SE San Carlos, Refugio Bartola (10°58.40'N, 84°20.30'W), 100 m elevation, collected by mercury vapor/ UV light trap, 2 males, 30.5.2002, leg. R. Brooks & Z. Falin, #NIC1BFC02 129 (1 KNHM, 1 UIC) ; Costa Rica: from same location, same date, and same collectors as holotype, male ( UIC) ; Puntarenas Province, Osa peninsula, Rd Rincon de Osa> Chacarita (8°42'-48'N, 83°15'- 29'W), car net, devastated forest & plantations, female, 10.12.2013, leg. Schülke & Grünberg ( MSC) ; Guanacaste, Palo Verde Biological Station, Sendero Natural la Venada (10°20.56'N, 85°19.53'W), fogging fungus covered log, 2 males, 16.7.2000, leg. J. Ashe, R. Brooks & Z. Falin, #CR1ABF00 148, ( KNHM) ; Rio Virilla , 1 male, 1 female, 2.1935, leg. A. Bierig ( FMNH) ; San José, 1935, leg. A. Bierig ( FMNH) ; Cuba: Varadero (81°11'W, 23°10'N), 2 males, 4 females, 16.6.2003, leg. Brachat (4 VAC, 2 UIC) ; Habana Prov. Guanabo , 17 males, 15 females, 14.2.1931, leg. A. Bierig (30 FMNH, 2 UIC) ; Sierra Bonilla, Cueva del Indio , male, 5.1.1929, leg. A. Bierig ( FMNH) ; Almendares , female, 12.1.1927, leg. A. Bierig ( FMNH) ; Rio Ariguanabo , 1 male, 1 female, 16.3.1929, 22.3.1930, leg. A. Bierig ( FMNH) ; Cueva del Indio, Tapaste Dis. , 2 males, 2.1928, leg. A. Bierig ( FMNH) ; La Lisa , female, 20.9.1931, leg. A. Bierig ( FMNH) ; Cojimar , male, 27.10.1928, leg. A. Bierig ( FMNH) ; Sierra del Rosario, Cayajabos , female, 25.3.1933, leg. A. Bierig ( FMNH) ; Loma del Candela, Güines , 5 females, 12.2.1938, leg. A. Bierig ( FMNH) ; Jamaica: Cane River Falls, St. Andrew , 500 ft. elev., leaves in spray, 1 male, 1 female, 31.7.1956, leg. P.F. Bellinger ( FMNH) ; Dominican Republic: Prov. Duarte, 7.5 mi. NE San Francisco de Macornis, Loma de Quita Espuela , litter nr. stream, 1 male, 800 ft. elev., 24.7.1991, leg. L. Herman #2599 ( AMNH) .

Diagnosis: The species extremely resembles D. schaumii in size and the light brown colouration. It can be differentiated from D. schaumii by the slightly more prominent eyes and the posteriorly more divergent head. D. schaumii has a more parallel head. The PW: EW ratio is 1.06, whereas it is 1.26 in D. angustiformis . The species is mainly characterised by the specific shape of the paramere, which is extremely asymmetric at apex. In contrast to these two species, the similarly sized D. brunneus is darker in colour with the anterior half of the pronotum light brown.

Description: Length 3.8 mm. Colouration: unicoloured brown, pronotum slightly lighter brown; abdominal segments III–VI slightly darker brown; legs and antennae lighter brown, except antennomeres IV to X darker.

Head: 0.49 mm long, 0.43 mm wide; eyes slightly prominent; EL: HL = 0.28; temples 1.8 times as long as eyes; temples divergent to posterior angles; PW: EW = 1.26; posterior angles widely rounded; posterior margin convexly curved; setiferous punctation deep and moderately dense; along impunctate midline with parallel row of setiferous punctures; on clypeus few punctures between rows, supraocular row of four punctures laterad to central row; several more supraocular punctures; postocular area more densely punctate; microsculpture weak; transversely and diagonally striate; surface slightly shiny.

Antennae as long as head and half of pronotum combined; first elongate antennomere thicker than following antennomeres; more than twice as long as its apical width; second conical antennomere twice as long as its apical width; third antennomere narrower than second and also twice as long as its apical width; length of following antennomeres decreasing; fourth slightly longer than wide; tenth antennomere slightly wider than long; all antennomeres pubescent and with few apical setae.

Pronotum: 0.68 mm long, 0.56 mm wide; widest in posterior half; slightly convergent to anterior angles; anterior angles widely rounded; anterior margin nearly semicircular; posterior angles widely rounded; lateral margin fine; in dorsal aspect, visible in posterior half; posterior margin convex; setiferous punctation moderately deep and sparse; along impunctate midline with three pairs of punctures; interstice between anterior pair nearly three times as wide as between posterior two pairs of punctures; three to four setiferous punctures laterad; along lateral margin numerous punctures with long setae; without microsculpture; with dense micro-punctation; surface shiny.

Elytra: 0.67 mm long, 0.72 mm wide; sides divergent to posterior angles; shoulders obtusely angulate; posterior angles nearly rectangular; posterior margin triangularly emarginate; setiferous punctation in irregular rows of seven to eight punctures; first row adjacent to suture line; two additional rows on disc; interstice between first row and second row twice as wide as between second row and third row; along lateral margin several setiferous punctures; ground-sculpture weakly coriaceous; slightly less shiny than pronotum.

Abdomen densely pubescent.

Aedeagus moderately slender; seminal vesical of endophallus 0.6 times as long as total length of central lobe; basal inner duct looped; ending in sclerotised forceps; two hooks at apex; paramere moderately thick; shaft in central part longitudinally folded; apical part largely widened; forming large triangular process; at base of triangle with two long apical setae; near acute apex with one shorter seta.

Spermatheca approximately circular; 0.33 mm in diameter; bursa copulatrix in lateral position to coiled duct; coiled duct with numerous irregular coils.

Etymology: The species name is a combination of the epithet angusti derived from the Latin word angustus meaning small and formis meaning shaped and refers to the narrow shape of the head compared to D. brunneus .

Figures

Figs 44: Fore-bodies of Diochus pumilio (A), D. panamaensis (B), D. angustiformis (C), D. brunneus (D), D. schaumii (E), D. argen-

Figs 26–29: Diochus maculicollis group: D. panamensis (26), and Diochus schaumii-group D. schaumii (27), D. angusti-

Fig. 39: Spermathecae of Diochus inornatus-group: D. schuelkei (A), D. plaumanni (B), D. tricolor (C), D. vicinus (D); Diochus maculicollis-group: D. brooksi (E), D. ecuadoriensis (F), D. maculicollis (G), D. pumilio (H), D. peruvianus (I), D. mexicanus (J), D. panamaensis (K); Diochus schaumii-group: D. angustiformis (L); scale bar: 0.1 mm.