Phloeosinus laricionis Faccoli & Sidoti

Faccoli, Massimo & Sidoti, Agatino, 2013, Description of Phloeosinus laricionis sp. n. (Coleoptera: Curculionidae, Scolytinae), a new bark beetle species from southern Europe, Zootaxa 3722 (1), pp. 92-100 : 93-98

Phloeosinus laricionis Faccoli & Sidoti , new species

Description. Male. Total length averaging 2.26 ± 0.11 mm (mean ± sd) and ranging 2.08–2.53 mm. Color of mature adults dark brown or black, shining; pronotum slightly darker than elytra ( Figs 1, 2). Frons with a moderately impressed, impunctate, smooth and shining concavity from the epistoma to the level of the eyes ( Fig. 3 ); area around concavity dull and finely punctate, spaces among punctures with feeble but visible reticulation. Upper margin of the concavity with a small tubercle emerging from the middle of frons ( Fig. 3 ). Frons with scattered, few, long yellow setae, directed centrally. Setae shorter in the upper part of frons ( Fig. 3 ). Antenna composed by scape, pedicel and 4 segments ( Fig. 4 ); club and funicle of the same color, uniformly dark-brown ( Fig. 2); club appearing 4-segmented, ovate, shining; club tip and sutures with abundant vestiture of uniformly short pale setae; first segment with straight sutures, second segment slightly arcuate, third segment strongly arcuate ( Fig. 5 ).

Pronotum short, stout, 1.44 ± 0.05 (1.36–1.56) times wider than long, widest at the base and strongly constricted in the anterior third, where the sides are strongly arcuate ( Fig. 1). Surface shining, densely, deeply and homogeneously punctured. Vestiture of moderately abundant yellow setae of two kinds, one of sparse, long and semierect setae directed posteriorly, and denser along lateral areas of pronotum; the other of very fine, fluffy pale setae adjoining to the surface and usually paired ( Figs 1, 6 ). Anterior margin of pronotum with a row of dense, short yellow setae ( Figs 1, 2, 6 ).

Elytra dark brown in mature specimens, paler than pronotum and body ( Figs 1, 2). Elytra 1.6 ± 0.03 (1.55– 1.69) times longer than wide, 2.6 ± 0.1 (2.43–2.81) times longer than pronotum. Anterior margin of elytra raised, granulated and wrinkled, especially on striae 2, slightly rounded and not interrupted in the scutellar area ( Figs 1, 2).

Sides subparallel, converging posteriorly in the posterior third ( Fig. 1). Disc shining. Vestiture like on pronotum: long, semierect yellow setae scattered on disc but denser on declivity and along the lateral margins of elytra, intermixed with denser short, fine, fluffy bifurcated setae adjoining to the surface ( Figs 1, 2). Interstriae apparently more hairy than striae. Elytral interstriae elevated, 1.5–2.0 times as wide as the striae; elytral striae with uniseriate rows of small, deep and closely spaced fine punctures; striae 4 and 6 not reaching the apex of elytra. Declivity broadly rounded, beginning at distal third of elytra; declivity with fine and acutely pointed, setiferous tubercles distributed along the odd interstriae 1–7; striae 2 on the declivity wide, strongly impressed but broadly convex to flat, shining, with few scattered short setae ( Figs 1, 2). Legs almost dark-brown, same color as elytrae ( Fig. 2).

Female. Similar to male, but frons flat, without concavity, only with a flat median punctated area ( Fig. 7 ); rest of frons hairy, punctated, finely sculptured but not granulated. Central tubercle of frons smaller and less easily visible. Striae 2 on the declivity slightly less impressed ( Fig. 7 ). Males and females similar in size.

Type material. All from the island of Sicily, in Italy. The material was collected in 2010–2012 from the locality of Primo Monte (37° 47' 08" N, 15° 03' 37" E, 1655 m a.sl.), Monte Vetore (37° 41' 27" N, 14° 59' 00" E, 1820 m a.s.l.), and Cubania (37° 45' 07" N, 15° 04' 37" E, 1330 m a.s.l.). The investigated specimens include the holotype and 60 paratypes, of which: 2 from Primo Monte, iv.2010; 6 from Monte Vetore, x.2010; 8 from Primo Monte, iv.2011; 31 from Monte Vetore, x.2011; 3 from Primo Monte 14.vi.2012; 9 from Monte Vetore, ii.2012; 1 from Cubania 14.vi.2012. All specimens were collected by A. Sidoti from Phloeosinus -killed P. nigra ssp. laricio.

Etymology. The Latin epithet, laricionis , was chosen to reflect the only host tree known, P. nigra ssp. laricio.

Collections and depositories. The holotype is deposited in the Natural History Museum, London ( England). Paratypes are distributed in the collections of the University of Padua ( Italy), Natural History Museum (London, England), Naturhistorisches Museum Wien (Vienna, Austria), and Miloš Knížek (Prague, Czech Republic).

Host plants and ecology. The only host plant so far known is P. nigra ssp. laricio. In the monitored stands, P. laricionis was found in the middle to upper part of the stem of young pine trees about 30 years old. P. laricionis was always associated with small pine bark beetle species of the genus Pityogenes Bedel and Pityophthorus Eichhoff infesting thin barks of stressed trees. Gallery systems are longitudinal, with one or two egg tunnels per system.

Differential diagnosis and identification key. Phloeosinus laricionis is morphologically very closely related to the Phloeosinus species living on cedars, P. ce d r i, P. acatayi and P. pfefferi , known respectively from Algeria and Morocco on Cedrus atlantica (Endlicher) , Turkey and Syria on Cedrus libani Richard , and Cyprus on Cedrus brevifolia (Hook.) . Along the declivity, all these species have the elytral interstriae 1–7 provided with small single tubercles. Phloeosinus laricionis can be distinguished from P. c e d r i and P. acatayi by the remarkably larger size, the tuberculate frons, the host plant and the distribution area. Although similar in size, P. laricionis may be separated from P. pfefferi by the smaller, deeper and closer fine punctures of the elytral striae making the elytral interstriae 1.5–2.0 times as wide as the striae; differently, P. pfefferi shows elytral striae with large, shallow and spaced points making the elytral interstriae as wide as the striae. Different hosts and distribution can also help in species separation.

The following identification key is intended to facilitate separating P. l a r i c i o n i s from morphologically similar Phloeosinus species. The arrangement of the species in the key is not phylogenetic.

1 Large, blunt tubercles along the declivity of the odd interstriae 1–7. Elytral striae with large, shallow, widely spaced punctures; elytral interstriae as wide as the striae...................................................................... 2

- Fine, acutely pointed tubercles along the declivity of the odd interstriae 1–7. Elytral striae with small, deep and close punctures; elytral interstriae 1.5–2.0 times as wide as the striae..................................................... 3

2(1) Small species, <2.2 mm long. Elytra covered by fluffy setae and dull surface. In Turkey and Syria on Cedrus libani ............................................................................................... P. acatayi Schedl

- Large species,> 2.2 mm long. Elytra with few fluffy setae and generally shining surface. In Cyprus on Cedrus brevifolia ............................................................................................ P. pfefferi Knížek

3(1) Small species, <2 mm long. Frons crenulate-granulate but without tubercle. Elytra brown. In Algeria and Morocco on Cedrus atlantica ................................................................................. P. cedri Brissout

- Large species,> 2 mm long. Frons punctate, with a small central tubercle (in males). Elytra black. In Sicily ( Italy) on Pinus nigra ssp. laricio ............................................................................ P. laricionis

Figures

FIGURE 3. Frons of male. Note central tubercle, concavity and setae distribution.

FIGURE 4. Whole antenna: note scape, pedicellus and the 4 following segments.

FIGURE 5. Antennal club. The sutures of the club are straight on the first segment, slightly arcuate on the second, and strongly arcuate on the third.

FIGURE 6. Male of Phloeosinus laricionis, lateral view of head and pronotum.

FIGURE 7. Frons of female. Note the flat median punctate area, without concavity.