Philonthus convexicollis Lynch-Arribálzaga, 1884

Chani-Posse, Mariana, 2010, Revision of the southern South American species of Philonthus Stephens (Coleoptera: Staphylinidae) 2595, Zootaxa 2595, pp. 1-70 : 21-22

Philonthus convexicollis Lynch-Arribálzaga, 1884

( Figs. 42–48, 145)

Philonthus convexicollis Lynch-Arribálzaga, 1884: 157 ; Bernhauer and Schubert, 1914: 333 (catalog); Bruch, 1915: 444 (catalog); Blackwelder, 1944: 132 (list); Frank, 1982: 38 (list); Herman, 2001b: 2788 (catalog); Chani-Posse, 2004: 230 (list).

Diagnosis. Philonthus convexicollis may be identified by the antennal segment 2 shorter than segment 3, the eyes about as long as temples, the distance separating medial interocular punctures on frons twice as large as distance separating medial punctures from lateral punctures, the male tergum 10 arcuate apically, and the apex of median lobe subacute. It differs from other southern South American species of Philonthus by the last segment of labial palpus 1.5 times as long as preceding segment, the submentum about 1.5 times as long as mentum, and the male sternum 8 deeply emarginate apically.

Redescription. Length of the body 6.8–7.5 mm. Coloration. Head castaneous- piceous to black; thorax and elytra castaneous-piceous to castaneous-brunneous; abdominal segments castaneous-piceous; first three antennal segments castaneous-brunneous, other segments castaneous-piceous, palpi and legs castaneousbrunneous.

Head about as long as wide (HW/HL= 1.1–1.0) and at basal third as wide as distal third in both sexes, distinctly narrower than pronotum (HW/PW= 0.77–0.72); 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 twice as large as distance separating medial punctures from lateral punctures; infraorbital ridge present, reaching postgenal ridge. Eyes about as long as temples (EL/TL= 1.00–0.85) seen from above. Antennae with segment 1 slightly shorter than segments 2 and 3 combined, segment 2 shorter than segment 3, segments 4–10 elongate. 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= 1.09–0.96), distinctly narrowed anteriad; 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. 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 longer than last segment (S1/S5= 1.4). Abdominal terga distinctly punctuate at basal area, distance separating punctures distinctly smaller than 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 slightly notched at middle. Tergum 8 in both sexes with posterior margin truncate.

Male genitalia. Sternum 8 deeply emarginate medio-apically ( Fig. 42). Tergum 10 wide and arcuate medio-apically ( Fig. 44), with four long subapical macrosetae and 2–6 apical setae. Sternum 9 deeply emarginate apically with basal portion asymmetrical, two long subapical macrosetae and three apical setae at each side ( Fig. 43). 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 elongate and entire, leaflike, reaching two thirds of median lobe length, each side with one row of sensory peg setae joined at apex ( Figs. 45–47). Internal sac with no distinctly sclerotized structures.

Female genitalia. Tergum 10 acute apically, with two long subapical setae and 8–10 long apical setae. Second gonocoxite with 2–5 strong setae along its outer margin, and stylus with two long apical setae ( Fig. 48).

Geographical distribution. Philonthus convexicollis is known from central Argentina, Chile (no locality data) and Paraguay (Asunción) ( Fig. 145).

Bionomics. According to Lynch-Arribálzaga (1884), P. convexicollis is found in manure and carrion, mainly during autumn and spring. Frank (1982) cites this species as parasitized by Laboulbeniales (Fungi, Ascomycetes).

Type material. Lectotype (here designated), ♀, with labels (no locality data): “Photo Bruch” (white), “ Philonthus convexicollis Fauv. n. sp. ”, “ Philonthus convexicollis Lynch Arribálzaga 1884 , syntypus ” (pink), “ Lectotype Philonthus convexicollis Lynch Arribálzaga 1884 / Des. Chani-Posse de Maus 2009 ” ( MACN).

Notes. Although the type locality and both male and female characters are given in the original description, there is no indication about how many specimens were examined by Lynch-Arribálzaga (1884). Another two female specimens labeled as syntypes became available to me but they are in bad condition and it is not possible to say in how far they agree with the original description. Of the three specimens found at the MACN labeled as syntypes, I hereby designate the individual which is in better condition and agrees with the original description as the lectotype.

Comments. Lynch-Arribálzaga (1884) cites “Habitat Chacabuco: in Provincia Bonaerensi occidentali” as the type locality for this species. I was not able to confirm this fact in the present designation.

Additional material: 59 specimens (19 ♂, 15 ♀, 25 unsexed)

ARGENTINA: Buenos Aires: 25.11.1905, C. Bruch, Philonthus convexicollis Lynch , in Bernhauer handwriting " Philonthus convexicollis Lynch ", 3 specimens ( MACN); Caseros, III-1932, 1 specimen ( MLPA). Jujuy: C. Bruch, Philonthus longicornis var. Steph., Philonthus atriseriatus Bernh. , 1 specimen ( MACN). La Rioja: VI-1932, 2 specimens ( MLPA). Mendoza: Sta. Rosa, Ñacuñan, 12-X-02, G. Flores, 1 ♂ ( IADIZA). San Luis: Q. de Lopez, 7km SE S. FcoMdeOro, 4-XII-00, S. Roig, 1 ♂ ( IADIZA). CHILE: A. Faz, 3 specimens ( AMNH). PARAGUAY: Asunción: January-March, B. Podtiaguin, 17 ♂, 15 ♀, 15 specimens ( AMNH).