Philonthus discoideus ( Gravenhorst, 1802 )

Chani-Posse, Mariana, 2010, Revision of the southern South American species of Philonthus Stephens (Coleoptera: Staphylinidae) 2595, Zootaxa 2595, pp. 1-70 : 26-27

Philonthus discoideus ( Gravenhorst, 1802)

( Figs. 54–59, 148)

Staphylinus discoideus Gravenhorst, 1802: 38 . For complete references see Herman (2001b).

Philonthus emelinae Coiffait & Sáiz, 1968: 354 ; Sáiz, 1971: 342 (list); Herman, 2001b: 2817 (catalog); Chani-Posse, 2004: 230 (list); Chani-Posse de Maus, 2009: 39 (syn.).

Diagnosis. Philonthus discoideus may be identified by its coloration, the eyes moderately longer than temples seen from above, and the distance separating medial interocular punctures on frons about four times as large as distance separating medial punctures from lateral punctures. It differs from other southern South American species of Philonthus by the abdominal terga 2 and 3 with elevated area between basal lines punctuate, and the posterior basal line straight medially.

Redescription. Length of the body 5.0–6.0 mm. Coloration. Head black; thorax castaneous-brunneous; elytra castaneous-piceous to castaneous-brunneous with medial and apical margins lighter, castaneousbrunneous to testaceous-brunneus; abdominal segments castaneous-piceous; antennae, palpi and legs castaneous-brunneous.

Head moderately to slightly wider than long (HW/HL= 1.3–1.1) and at basal third as wide as distal third in both sexes, about as wide as to slightly narrower than pronotum (HW/PW= 0.97–0.88); dorsal surface coarsely and moderately punctate, with three to four postocular punctures and three to four epicranial punctures; distance separating medial interocular punctures on frons about four times as large as distance separating medial punctures from lateral punctures; infraorbital ridge present, extending not far beyond postgenal ridge. Eyes moderately longer than temples (EL/TL= 1.20) seen from above. Antennae with segment 1 as long as segments 2 and 3 combined, segments 2 and 3 subequal in length, segments 4–6 quadrate, segments 7–10 transverse. Maxillary palpus with segment 2 not swollen, no more than twice as long as its maximum width; last segment fusiform, about 1.5 times longer than segment 3. Submentum about 1.5 times as long as mentum. Labial palpus with last segment 1.4–1.8 times as long as preceding segment. Neck more than 0.5 times as wide as head at widest point (NW/HW= 0.7).

Pronotum about as long as wide (PW/PL= 1.00–0.97), slightly narrowed anteriad to parallel-sided; dorsal surface of pronotum with two rows of punctures, each with five punctures. Hypomeron not visible in lateral view. Basisternum with medial longitudinal carina moderately developed, bulbous. Metasternum with circummesocoxal ridge broadly rounded medially. Elytra at sides moderately to distinctly longer than pronotum at midline (EtL/PL=1.4–1.2), distinctly longer than elytra along suture (EtL/Etl= 1.8–1.6); transverse distance between punctures about as large as to distinctly smaller than diameters of punctures (Fig. 2). Both front and middle tarsi as long as front and middle tibiae; first segment of hind tarsus as long as segments 2 and 3 combined, and shorter than last segment (S1/S5= 0.8). Abdominal terga moderately punctuate at basal area, distance separating punctures about equal to diameters of punctures; terga 2 and 3 with elevated area between basal lines punctuate, posterior basal line straight medially. Male sternum 7 with apical margin straight. Tergum 8 in both sexes with posterior margin arcuate.

Male genitalia. Sternum 8 moderately emarginate medio-apically. Tergum 10 truncate medio-apically ( Fig. 55), with two long subapical macrosetae and four short apical setae. Sternum 9 with a concave emargination apically and one apical seta at each side ( Fig. 54). Aedeagus with median lobe gradually narrowed from apical third; apex of median lobe subacute (in dorsal view) and simple in its apical fourth (in lateral view); paramere divided into two branches along most of its length, both close to each other reaching two thirds of median lobe length, each with 3–5 sensory peg setae at apex ( Figs. 56, 57). Internal sac without sclerotized structures.

Female genitalia. Tergum 10 concave medio-apically ( Fig. 58), with two long subapical macrosetae and two short apical setae. Second gonocoxite with 2–5 strong setae along its outer margin, without stylus and with one long apical seta ( Fig. 59).

Geographical distribution. Philonthus discoideus is a Palearctic species, which was introduced to various regions of the world, and it is now considered a cosmopolitan species ( Smetana 1995). The first records of its presence in the Neotropical region (Herman 2001) may indicate an earliest arrival and establishment in Cuba. Until the present work, P. discoideus was only known in South America from Venezuela (Herman 2001) and Argentina ( Bruch 1915). Bolivia, Brazil, Colombia, Chile, Panamá and Paraguay are new records. In southern South America ( Fig. 148) it is known from few localities in Argentina (Tucumán), Bolivia (Vaca Diez), Brazil (Pernambuco), Chile (Santiago and Curicó), and Paraguay (Asunción).

Bionomics. Smetana (1995) found this species to occur in habitats associated with human settlements, cattle droppings and other organic debris. Frank (1982) also cites this species as parasitized by Laboulbeniales (Fungi, Ascomycetes).

Type material. Lectotype of Philonthus discoideus , ♂, with labels: “6116”, “ discoideus Gr. *”, “Zoo. Mus. Berlin ”, “ Lectotype Staphylinus discoideus Gravenhorst A. Smetana des. 1991” ( ZMHB) . Paralectotypes: 2♂♂, 4♀♀, with labels: “Zool. Mus. Berlin ”, “Hist. –Coll. ( Coleoptera ) / Nr. 6116 / Philonthus discoideus Grvh / Germania / Zool. Mus. Berlin ” , one ♀ with additional label “ thor. seriebus dorsal. Altera 5- altera 4-punctata Austr. Sch. ” ( ZMHB) .

Holotype of Philonthus emelinae , ♂, with labels: “ Chile / Curicó ”, “ Romeral / 25-XII-1963 ”, “ HOLOTYPE ”, “ Philonthus emelinae Coiffait y Saiz ” ( FSC).

Additional material: 24 specimens (5 ♂, 15 ♀, 4 unsexed)

ARGENTINA: Tucumán: Famaillá , Philonthus discoideus Grav. , 1 ♂ ( MACN) . BOLIVIA: Vaca Diez : Beni, 8.VIII.1990, Riberalta, FMHD 90-148, P. Parrillo Leg, Field Mus. Nat. Hist., 1 ♀ ( FMNH) . BRAZIL: Pernambuco: Recife , 9 July 1944, R. E. Wenzel, in excrement, 1 ♀ ( FMNH) . CHILE: Santiago: El Arrayan, X.1979, L. E. Peña leg., Field Mus. Nat. Hist., 1 ♂ ( FMNH) . COLOMBIA: Grenada: Balthazar (Winward Side), H. Smith, c. Epplsh. Steind. D., in Bernhauer handwriting " discoideus det. Bernhauer ", Chicago NHMus Bernhauer Collection , 1 ♂ ( FMNH) . CUBA: Camagüey: Portugalette , VIII.1929, Field Mus. Nat. Hist. 1966 A. Bierig Collection, Acc. Z. 13812, 1 specimen ( FMNH) . Pinar del Río: Viñales , 17.VIII.1928, Field Mus. Nat. Hist. 1966 A. Bierig Collection, Acc. Z. 13812, 1 specimen ( FMNH) . MEXICO: Veracruz: Cordoba, Dr. A. Fenyes, in Bernhauer handwriting "discoideus det. Bernhauer ", Chicago NHMus Bernhauer Collection, 1 ♂ ( FMNH) . PANAMA: Arussielles ( Argüelles ?), VIII.1930, Field Mus. Nat. Hist. 1966 A. Bierig Collection, Acc. Z. 13812, 2 specimens ( FMNH) . PARAGUAY: Asunción: January – March, B. Podtiaguin , 1 ♂ 10 ♀ ( AMNH) . VENEZUELA: Zulia: Perija, San Jose- El Guamito / Aponcito , Hacienda / Grano de Oro-15mSE, VI.1982, at light, FMHD 82-490, V. Linares Leg, Field Mus. Nat. Hist., 3 ♀ ( FMNH) .