Drusilla italica ( BERNHAUER , 1903)

Assing, Volker, 2006, On the Italian species of Drusilla L, 1819, with a note on D. taygetana A (Coleoptera: Staphylinidae, Aleocharinae), Beiträge Zur Entomologie = Contributions to Entomology 56 (2), pp. 281-296 : 287-293

Drusilla italica ( BERNHAUER, 1903) ( Figs 7-52 , Map 2 )

Type material

Lectotype  [dissected prior to present study, spermatheca damaged]: Vallo Lucania, Süditalien, Solari / meridionalis Fauvel / italicus Bernh., Type / Chicago NHMus., M.Bernhauer Collection / Drusilla italica (Bh.) V.I. Gusarov det. 1993 / Lectotypus  Astilbus italicus Bernhauer desig. V. Assing 2006 / Drusilla italica (Bernhauer) det. V. Assing 2006 ( FMNH).

Additional material examined:

Form 1: Campania: 2 exs. , Vallo Lucano, San Biase, 1904, leg. Solari ( NHMW, cAss) . Calabria: 22 exs. , Sant’Eufemia d’Aspromonte, fiumara Crasta , 650 m, 4.V.1993, leg. Angelini & Sabella (cAss); 2 exs. , Calabria, Sant’Eufemia d’Aspromonte, fiumara Crasta , 6.V.1993, chestnut forest, leg. Angelini & Sabella ( MCSNV); 3 exs. , same locality, 550 m, 31.V.1993, leg. Angelini ( MCSNV); 1 ex. , same locality, 630 m, 31.V.1993, leg. Angelini & Sabella (cAng); 7 exs. , same locality, 600 m, 23.VI.1993, leg. Angelini (cAng); 5 exs. , below S. Eufemia-Piani Aspromonte , 800 m, Quercus ilex forest, 21.VI.1993, leg. Angelini ( MCSNV); 2 exs. , same locality, 650 m, chestnut forest, 31.V.1993, leg. Angelini & Sabella (cAng); 1 ex. , same locality, 1905, leg. Paganetti ( DEI); 8 exs. , same locality, leg. Paganetti ( DEI, NHMW); 1 ex. , same locality, VII.1957 ( MCSNV); 5 exs. , Caraffa del Bianco ( RC), M. Mena, grassland, 14.IV.1997, leg. Angelini (cAss); 3 exs. , Africo ( RC), grassland, 50 m, 7.XI.1997, leg. Angelini (cAss); 1 ex. , Africo ( RC), 50 m, grassland, 23.I.2003, leg. Angelini (cAng); 1 ex. , same data, but 29.V.2003 (cAng); 8 exs. , Femuzzano ( RC), 70 m, grassland, 23.I.2003, leg. Angelini (cAss); 11 exs. , S. Luca env. ( RC), grassland, 8.XI.1997, leg. Angelini (cAss); 1 ex. , S. Luca, loc. S. Giorgio , 550 m, stream bank, 13.X.1993, leg. Angelini ( MCSNV); 1 ex. , San Luca ( RC), grassland, 200 m, 23.I.2003, leg. Angelini (cAng); 1 ex. , S. Luca, road to Santuario di Polsi , 740 m, Quercus ilex forest, 13.X.1993, leg. Angelini (cAng); 3 exs. , S. Alessio ( RC), 490 m, oak forest, 2.V.1993, leg. Sabella (cWun); 10 exs. [originally identified as D. canaliculata ], S. Alessio , 470 m, chestnut forest, 2.V.1993, leg. Angelini & Sabella ( MCSNV, cAss); 1 ex. , Antonimina ( RC), 800 m, mixed forest, 3.V.1993, leg. Angelini & Sabella (cWun); 7 exs. , Antonimina , 600 m, Quercus ilex forest, 1.VI.1993, leg. Angelini & Sabella ( MCSNV, cAng); 1 ex. , Antonimina , 800 m, Quercus ilex forest, 3.V.1993, leg. Angelini & Sabella (cAng); 1 ex. , same data, but 600 m (cAng); 6 exs. , Antonimina, 1905, leg. Paganetti ( DEI); 3 exs. , Antonimina, leg. Pagenetti ( NHMW); 11 exs. , Cimina, leg. Paganetti ( DEI, NHMW); 2 exs. , Cimina , 650 m, Quercus ilex forest, 12.X.1993, leg. Angelini & Sabella ( MCSNV); 7 exs. , Gerace, leg. Paganetti ( NHMW); 3 exs. , Samo ( RC), Fiumara S. Venere, Mastix , 7.XI.1997, leg. Angelini (cAng); 3 exs. , Samo ( RC), Fiumara S. Venere, grassland, 14.IV.1997, leg. Angelini (cAss); 1 ex. , Podàrgoni ( RC), 600 m, stream, 22.VI.1993, leg. Angelini (cAng); 6 exs. , Isola di Capo Rizzuto ( KR), 14.XII.1997, leg. Angelini (cAss); 6 exs. [1 teneral], Cetraro, Aron stream ( CS), 16.VI.1994, leg. Angelini (cAss); 2 exs. , Fagnano Castello [CS], Lago Trifoglietti , 1300 m, VI.1994, Angelini & Sabella (cAss); 1 ex. , Roseto ( CS), grassland, 28.XII.1997, leg. Angelini (cAng); 8 exs. , Monti Orsomarso , 670 m, 4.VIII.1989, leg. Angelini (cAss, cWun); 3 exs. , Monti Orsomarso, Grisolia ( CS), loc. Pantanelle , 700 m, beech forest, 17.VI.1997, leg. Angelini (cAss); 5 exs. , same locality, 670 m, beechforest, 4.VIII.1989, leg. Angelini (cAng); 3 exs. , Monti Orsomarso, Grisolia ( CS), 8.VIII. 1992, 700 m, beech forest, leg. Angelini (cAng); 3 exs. , Monti Orsomarso, Valle Argentino ( CS), 250 m, oak forest, 11.VIII.1990, leg. Angelini (cAng); 1 ex. , Valle Argentino , oak forest, 16.VI.1991, leg. Angelini (cAng); 1 ex. , Monti Orsomarso, S. Maria del Monte ( CS), 1350 m, chestnut forest, 6.VIII.1989, leg. Angelini (cAng); 3 exs. [one specimen with worker of Formica sanguinea attached to the pin], Sila Grande ( CS), Lago Arvo , south shore, 1290-1350 m, 18.-19.V.1994, leg. Schulz, Güsten & Sanetra (cAss); 3 exs. , E Cittanova, Piani di Gióia, Pso. del Mercante , 500 m, 30.VI.2001, leg. Wolf (cSch, cAss) . Basilicata: 1 ex. , Monte Sirino ( PZ), 1300 m, 26.VI.1998, leg. Daccordi (cAss); 5 exs. , M. Sirino, Timpa Pellinera ( PZ), 900 m, beech and oak forest, 30.VII.1989, leg. Angelini (cAng); 1 ex. [teneral], M. Sirino, L. Sirino env. ( PZ), 800 m, oak forest, 25.VII.1989, leg. Angelini (cAng); 1 ex. , Lagonegro ( PZ), ponte La Cala, 600 m, 6.VIII.1990, leg. Angelini (cZan); 3 exs. , Episcopia ( PZ), 520 m, bank of Sinni river , trap with acetic acid, 19.VI.2002, leg. Angelini (cAng, cAss); 1 ex. , Abriola , La Maddalena ( PZ), 1400 m, trap with acetic acid, 30.III.2002, leg. Angelini (cAng); 1 ex. , Castelsaraceno ( PZ), Cogliandrino stream, trap with acetic acid, 800 m, 14.IV.2004, leg. Angelini (cAng); 1 ex. , Rivello, Monte Caccovello ( PZ), 630 m, oak forest, 29.VII.1989, leg. Angelini (cAss) . Puglia: 23 exs. , Taranto env., 17.XII.2000, leg. Montemurro (cZan, cAss); 16 exs. , Taranto env., 22.X.2000, leg. Montemurro (cZan) . Sicilia: 1 ex. , Monti Nebrodi , E Portella Femmina Morta, SE-slope, 37°55N, 14°39E, 1560 m, 2.IV.2001, leg. Schülke (cSch); 1 ex. , Messina , 1906, leg. Leonhard (cAss); 2 ex. , Messina , 26.IV.1943 ( NHMW); 1 ex. , Ficuzza , 1906, leg. Leonhard (cAss); 2 exs. , Fiumara di Niceto , 1.IX.1995, leg. Adorno (cZan) .

Form 2: Abruzzi: 1 ex., Aquila ( NHMW) . Lazio: 2 exs., Camerata Nuova, 1909, leg. Krüger ( NHMW, cAss) ; 1 ex., Itri , 25.IV.1977, leg. Zampetti (cAss) . Campania: 17 exs., estuary of Volturno river ( CE) , detritus, 25.III.1994, leg. Angelini (cAng, cAss); 10 exs., Salerno, Com. Capaccio, E Paestum, west side of Mte. Soprano , 350 m, 13.X.2000, leg. Wolf (cAss, cSch) ; 1 ex., Rofrano ( SA) , 400 m, 11.IV.2004, leg. Zanetti (cZan); 1 ex., Cilento, M. Cervati ( SA) , 1100 m, beech forest, 31.VII.1989, leg. Angelini (cAng). Basilicata: 3 exs., Policoro ( MT) , 14.IX.1999, leg. Angelini (cAss); 1 ex., Policoro ( MT) , 25.I.1976, leg. Angelini (cWun); 1 ex., Policoro ( MT) , 23.IV.1978, leg. Angelini (cZan); 1 ex., Policoro , 4.I.1976, leg. Angelini (cAng) ; 1 ex., Policoro , 24.VII.1994, leg. Angelini (cAng) ; 1 ex., Policoro , 2.VI.1989, leg. Angelini (cAng) ; 2 exs., Valsinni ( MT) , 180-200 m, rive F. Sinni , 13.X.2002, leg. Angelini (cAng) ; 1 ex., same data, but 19.VI.2002 (cAng) ; 1 ex., Potenza , X.1995, leg. de Marzo (cAss) ; 1 ex., Pietrapertosa, M. Impiso ( PZ) , 1200 m, 6.VII.1989, leg. Angelini (cAss); 2 exs., Accettura, torrente Salandrella ( MT) , 425 m, oak forest, 14.V.1989, leg. Angelini (cAng, cAss); 3 exs., Laghi di Monticchio ( PZ) , 660 m, 19.VI.1988, leg. Angelini (cAng); 1 ex., road Lago Pantano-La Sellata ( PZ) , 950 m, 30.VI.2002, leg. Angelini (cAng); 3 exs., same data, but 27.VII.2002 (cAss) ; 1 ex., same data, but 900 m, 14.IV.2002 (cAng) ; 1 ex., Accettura, Monte la Cróccia ( MT) , 1000 m, oak forest, 1.V.1990, leg. Angelini (cAng); 2 ex., Pollino, San Severino ( PZ) , bosco Magnono , 800 m, beech forest, 19.XII.1993, leg. Angelini (cAng) ; 3 exs., Corleto Perticara ( PZ) , 770 m, 1.VII.1989, leg. Angelini (cAng); 1 ex., Corleto Perticara , 970 m, 14.V.1989, leg. Angelini (cAng) ; 1 ex., L. S. Giuliano ( MT) , Ponte Cagnolino , 18.VIII.1993, leg. Angelini (cAng) . Puglia: 1 ex., L. San Giovanni, Gargano, leg. Holdhaus (cAss) ; 4 exs., F. Lato, 10 km from estuary ( TA) , 2.I.1977, leg. Angelini (cZan, cAss); 1 ex., 5 km E Taranto, Circummarpiccolo ( TA) , 5.XII.1993, leg. Angelini (cAss); 1 ex., Gravina di Puglia ( BA) , 400 m, 21.IV.1987, leg. de Marzo (cAng); 1 ex., estuary of Bradano river ( TA) , 15.II.1985, leg. Angelini (cAng); 1 ex., San Basilio ( TA) [“Murgien, San Basilio”], leg. Paganetti ( NHMW); 1 ex., Taranto , 21.VII.1956, leg. Viglietta (cWun). Locality not specified : 1 ex.: Italia ( DEI) .

Redescription

4.0-5.5 mm. Coloration dark brown to blackish, pronotum and elytra often slightly to distinctly paler than head and abdomen; legs yellowish to pale brown; antenna brown to dark brown, with the basal 3-4 antennomeres reddish to reddish brown.

Head with posterior angles more or less marked to smoothly rounded; puncturation distinct, but rather fine and shallow, moderately dense; median dorsal area sometimes punctate; interstices in lateral dorsal area narrower than diameter of punctures; microsculpture variable, ranging from shallow and indistinct to pronounced ( Figs 7-8 , 21-24 ). Antenna of variable length and proportions ( Figs 41-43 ).

Pronotum with very dense puncturation; punctures denser and more distinct than those of head; interstices with variable, shallow to distinct, but occasionally practically obsolete microsculpture, and with weak to distinct shine; fine furrow along midline not reaching anterior and posterior margins; sexual dimorphism less pronounced than in D. canaliculata ( Figs 7-8 , 21-24 ).

Elytra 0.55-0.60 times as long as pronotum; laterally more or less extensively and shallowly impressed; puncturation much coarser than that of pronotum; interstices very narrow and with some shine ( Figs 7-8 , 21-24 ).

Abdomen without or with very superficial microsculpture; puncturation moderately dense on anterior tergites and very sparse on posterior tergites; posterior margin of tergite VII with barely noticeable rudiment of a palisade fringe.

: posterior two thirds of pronotum with median impression of variable depth (but always shallower and less extensive than in D. canaliculata ) ( Figs 7 , 21-23 ); posterior margin of tergite VIII serrate and broadly concave, this concavity of variable depth, often somewhat angulate in the middle, and laterally often delimited by pronounced tooth-like process ( Figs 9-10 , 25-31 ); sternite VIII strongly tapering posteriorly, its hind margin weakly convex ( Figs 11 , 32 ); median lobe of aedeagus rather uniform ( Figs 12 , 44-46 ).

: posterior half of pronotum with shallower median impression ( Figs 8 , 24 ); posterior margin of tergite VIII weakly serrate and more narrowly concave than in , this concavity of variable depth ( Figs 13-15 , 33-39 ); posterior margin of sternite VIII usually very shallowly concave ( Figs 16 , 40 ); spermatheca of rather variable shape, with strongly sclerotised, usually almost black capsule and with subproximally often narrowed and proximally more or less distinctly dilated duct ( Figs 17-20 , 47-52 ).

Intraspecific variation

External characters such as size, coloration, microsculpture, and pronotum shape, the secondary sexual modifications of the pronotum and the abdominal tergite VIII, as well as the morphology of the spermatheca were observed to be subject to pronounced varia- tion. This observation at first suggested that D. italica was in fact a complex of two or more species or subspecies, particularly because the spermatheca is usually of rather constant shape and of high taxonomic significance in the genus ( ASSING 2005b). Based on a systematic and comparative study of these characters and a zoogeographic analysis, several forms or character constellations, as well as zoogeographic trends were identified:

Specimens from the extreme south of mainland Italy (from southern Puglia and southern Campania to Calabria) and from Sicily ( Map 2 ) - hereafter referred to as form 1 - tend to have a distinctly microsculptured head and pronotum, usually paler, light to dark brown pronotum and elytra, a usually more slender and more convex (cross-section) pronotum ( Figs 21-24 ), weakly marked posterior angles of the head, and a spermatheca with a proximally variable, but generally rather weakly dilated and subproximally not distinctly narrowed duct ( Figs 47-52 ). Material from Sicily is characterised by larger average size than beetles from mainland Italy, which is one reason why they were occasionally misidentified as D. canaliculata in the collections examined. The lectotype of D. italica belongs to form 1.

Form 2 is characterised by a more shiny appearance due to shallower microsculpture of head and pronotum, more uniform dark coloration (pronotum and elytra usually as blackish as head and abdomen), a usually slightly shorter and less convex pronotum ( Figs 7-8 ), and a spermatheca with a proximally distinctly dilated and subproximally often constricted duct ( Figs 17-20 ). This character constellation was often observed in material from the region comprising northern Campania, Lazio, Abruzzi, Basilicata, and Puglia ( Map 2 ).

In some regions such as Campania, Basilicata, and southeastern Puglia, both forms occur. Also, transitional character states were observed not only for the external characters, but also for the shape of the spermatheca, which is quite variable also within the populations here referred to as form 2 ( Figs 47-52 ). Finally, two specimens seen from Camerata Nuova (Lazio) - in the north of the range of form 2 (see square in Map 2 ) - have the external characters typically found in form 1, but a spermatheca similar to that of form 2. If the two forms represented subspecies, such an intermediate character constellation should be expected in the areas where both distributions overlap, but not in the north of the range of form 2. Consequently, in view of the distribution of morphological characters outlined above and the zoogeographic data, the observed variation is attributed to clinal rather than (sub-)specific variation.

Distribution and bionomics

The distribution of this species is confined to the south of mainland Italy and Sicily, with the northernmost records from Lazio, Abruzzi, and the Monte Gargano in northern Puglia ( Map 2 ). Records from northern Italy ( LUIGIONI 1929, PORTA 1926, ZANETTI 1995) are doubtlessly based on a confusion with other species. The material examined was collected at altitudes of 50-1560 m, both in pastures and in different types of deciduous forests (oak, beech, chestnut). On one occasion, three specimens were found in a nest of Formica sanguinea LATREILLE. Adult beetles were found throughout the year: January (16 exs. /6 records), February (1/1), March (19/3), April (13/7), May (54/15), June (51/16), July (18/10), August (22/7), September (5/2), October (33/7), November (17/3), December (33/5). Teneral adults were collected in June and July.

Figures

Map 2: Distribution of Drusilla italica (open circles: form 1; filled circles: form 2; sqare: specimens from Camerata Nuova) in southern Italy, based on examined records.

Figs 7-20: Drusilla italica, form 2:  forebody (7);  forebody (8);  tergite VIII (9); posterior margin of  tergite VIII (10);  sternite VIII (11); median lobe of aedeagus in lateral view (12);  tergite VIII (13); posterior margin of  tergite VIII (14-15);  sternite VIII (16); spermatheca (17-20). Scale bars: 7-8: 1.0 mm; 9-20: 0.2 mm.

Figs 21-43: Drusilla italica, form 1:  forebody (21-23);  forebody (24);  tergite VIII (25); posterior margin of  tergite VIII (26-31);  sternite VIII (32);  tergite VIII (33); posterior margin of  tergite VIII (34-39);  sternite VIII (40); antenna (41-43). Scale bars: 21-24, 41-43: 1.0 mm; 25-40: 0.2 mm.

Figs 44-52: Drusilla italica, form 1: median lobe of aedeagus in lateral view (44-46); spermatheca (47-52). Scale bars: 0.2 mm.