Hoplia (Hoplia) meridiana Uliana, Liberto

Leo, Piero, 2017, On the taxonomy of the Italian endemic Hoplia dubia (Rossi, 1792), with the description of two new species (Coleoptera: Scarabaeidae: Melolonthinae), Zootaxa 4320 (2), pp. 201-224 : 206-210

Hoplia (Hoplia) meridiana Uliana, Liberto , and Leo, new species

( Figs. 4–8 , 14–15 , 20–21 , 25 , 32 )

Specimens examined. A total of 1533 ♂, 39♀ . Holotype: Italia, Basilicata (MT), Foce F. Sinni, leg. F. Callegari (♂, MSNVE) . Paratypes: see Table 3.

Integrative and comparative description. For variable characters, the condition of the holotype is between square brackets.

Male. Habitus as in Figs. 4, 6–8 , 32 .

Size. Larger than H. dubia , similar to H. messapia . PBL: 5.8–7.5 mm [6.2], average 6.6 mm; TBL: 7.1–9.1 mm [7.2], average: 7.9 mm: MBW: 3.5–4.6 mm [4.0], average 4.2 mm.

Color. Elytra most commonly light brown [as in holotype], less commonly dark brown, rarely black.

Scales ( Figs. 14–15 ). Shape: in general, scales squatter than in H. dubia and quite similar to H. messapia , although smaller. On the head, elliptical to oval, not bristle-like. On pronotum and scutellum broadly elliptical or oval to round. On elytra elliptical to almost round, generally with acute apex [as in holotype], on average more slender than those of pronotum and of pygidium. On pygidium, oval to round with narrowly acute base and broadly rounded to truncate apex, on average broader than on pronotum. Color: on head, nacreous to pale green or cyan. Pronotum dichromatic, with rare exceptions. Dichromatism is generally scarcely evident [so in the holotype], with only few scales of different color near the anterior and the posterior margins. Color change can be gradual or abrupt from the discal area to the edges [gradual]. Discal area most commonly yellow to ochre, but can vary to light green [yellow]. Marginal areas, at least near the angles and the lateral margins [as in holotype] but sometimes along a broader stripe (maximum extension anyway narrower than in H. messapia ), with a paler hue, shifting to nacreous, pale green, or cyan. An irregular row of similar scales commonly present along the basal margin of elytra [almost absent], the rest of their surface and scutellum with scales similar to those on the pronotal disc, sometimes with color variable across the scales instead than uniform, which is the most common condition [uniform]. On propygidium, pygidium, ventral side and legs, similar to the margins of pronotum. Color in general more saturated than in H. dubia and H. messapia . Arrangement: adpressed or indistinctly raised from the integument. On head present and sparse on frons and vertex. On pronotum, basal "whirls" observed in H. dubia are absent: scales directed towards the midline may be widely present, but marginal scales directed forward are missing. On elytra, well spaced: in the discal area the transversal distance between two scales roughly 1.0–1.5 times the width of one scale.

Setae. In general, evidently shorter than in the other two species. Longest setae of pronotum about 0.2–0.3x the length of pronotum and 0.6–0.8x the width of scutellum ( Figs. 6 , 14 ). Length not uniform, decreasing towards the base along a broad medial area and along the base in general. In the medial basal third setae are shorter, uniformly measuring 0.3–0.5x the longest setae.

Scutellum with setae short and thick, bristle-like, similar to those along the base of the pronotum and of the elytra, although shorter and generally slightly thicker. Their length much shorther than half the length of the scutellum, and close to 2x the length of a scale, or less ( Figs. 20–21 ).

Elytra with setae much shorter than those of H. dubia and H. messapia , bristle-like, about 1.5–3.0 times as long as one scale.

Morphology. Clypeus about 2.5–3.1 [2.6] times wider than long (average: 2.8). Sides of pronotum evenly curved [so in the holotype] to slightly marked by a broadly rounded angle or a sinuation at mid-length, less evident than in H. messapia , parting a more rounded basal portion from a less rounded to straight distal portion. Sutural region of elytra, compared to the rest of the surface, flat [as in holotype] to raised and "swollen". Pygidium W/L = 1.35, as in H. messapia .

Protibia, on average, slightly broader than H. dubia and more similar to H. messapia . With particular reference to H. dubia , teeth blunter, the basal tooth less protruding, generally obtuse.

Protarsomere shorter and stouter than in the other two species ( Fig. 25 ).

Female. Habitus as in Fig. 5 .

Color. Tarsi rusty orange to dark brown. Lighter color of tibia and femora, brown to rusty orange, observed in about 60% of specimens.

Scales. Marginal band of pronotum composed of nacreous cyan-green scales, on average evidently broader and more abruptly defined than that of syntopic males. Color of elytral scales commonly less uniform than in males, with higher frequency of cyan-green scales. The latter, in rare cases, widespread on the entire surface and representing the majority of scales.

Morphology. Elytra different from that of the male: sides more curved, narrowing in the distal part and therefore overall shape shifting from subquadrate to more-or-less oval. Overall difference from the condition of the male is variable, from scarcely perceivable to distinct. Pygidium almost flat to slightly more convex than in males, ratio W/L: 1.30.

Variation. While the condition of setae shows no relevant variability, other characters and notably color, vary significantly. The rate of variability appears to be considerably different across the examined populations, therefore we provide a short account for each population/area examined.

Isola di Capo Rizzuto (58♂, 2♀): population showing a high frequency of phenotypes with dark elytral integuments. About 83% of examined males have brown to dark brown elytra. Some of them ( Fig. 8 ) have scales of dorsal and ventral side smaller and slender than usual, more distant from each other and hence shifting towards the condition of H. dubia , although mantaining a distinct, stouter shape from the scales of the latter. The state of other diagnostic characters (setae of pronotum, scutellum, elytra; color of scales) do not pose any doubt about their specific assignment; however, given the unusual overall aspect we decided to exclude this population from the type series since most of them would be not suitable for neotype institution nor as reference specimens for identification.

Sicily, Messina (13♂): size slightly smaller than the average.

Campania (217♂, 4♀): within each population there is a significant variability in color both of the elytral integument, going to pale brown to dark brown, rarely black; and of the scales vestiture, going from ochre to green, either uniform or with scales of different color sparsely mixed across the dorsal side. Intermediate conditions are found for both characters, as well as all the different combinations between color of the scales and color of the elytra. Dark elytra are found in about 48% of specimens, green vestiture in about 15%.

Basilicata including topotypical population: in spite of the large amount of specimens examined (over 1150), these populations exhibit the lower variability in terms of color. Specimens with dark elytral integuments are absent, as well as specimens with color of scales significantly departing from the most common yellow-ochre condition. The elytral suture is almost constantly flat.

Derivatio nominis. From the latin adjective "meridianus", meaning "southern", "coming from the south", due to this species being endemic to southern Italy.

Distribution. Hoplia meridiana is scattered along southwestern coast of Italy, from the Salerno Gulf to the sandy beaches of the Ionic Arc west of Taranto, and in eastern Sicily (Messina) ( Fig. 27 ). A single ancient specimen referable to this species is labeled "Castelbuono" ( Arnone 2010, as H. dubia ). Although, for ecological reasons, it cannot have been collected in this inland locality, it is not clear to us whether to consider it just a mistaken locality label, or if actually a population exists or existed in the few sandy shores next to Castelbuono (see map in Audisio et al. 2003: 120).

After interviewing most of the collectors, we know that most or all of the specimens coming from the R. N. O. Bosco Pantano di Policoro (including those labeled "Foce F. Sinni", see "Material and methods") were actually collected within the municipal territory of Policoro, which is traditionally the more attractive part of the Reserve for collectors. Only a tiny portion of the Reserve falls into Rotondella municipality, whose coastal dunes lay at a trifling distance from those of Policoro municipality, and share the same vegetation pattern.

Figures

FIGURE 27. Known distribution of the species of the Hoplia dubia species group.

FIGURES 4 – 6. Habitus of Hoplia meridiana in dorsal and lateral view. 4, male (Capaccio, Laura Beach); 5, female (Policoro); 6, male (Policoro).

FIGURES 7 – 8. Hoplia meridiana, extremes of variability in the habitus of males (the more typical color form shown in Fig. 4). 7, dark integument and extensively green scales, with metallic sheen (Capaccio, Varolato Beach). 8, rare phenotype with dark integument and unusually reduced scales (Isola di Capo Rizzuto, contrada Sovereto).

FIGURES 12 – 17. Hoplia dubia species group. Details of scale vestiture of dorsal side (12, 14, 16) and pygidium (13, 15, 17), male specimens. 12 – 13, Hoplia dubia (Marina di Vecchiano); 14 – 15, H. meridiana (Policoro); 16 – 17, H. messapia (Cesine, Le Vernole).

FIGURES 18 – 23. Hoplia dubia species group. Details of scutellar area in oblique (18, 20, 22) and dorsal (19, 21, 23) view, male specimens. 18 – 19, Hoplia dubia (Marina di Vecchiano); 20 – 21, H. meridiana (Policoro); 22 – 23, H. messapia (Torre Mozza). Note the difference between scutellar setae (thin in H. dubia, thick in H. meridiana and H. messapia) and the differences on the relation between the setae of scutellum and periscutellar setae of elytra (reciprocally similar for length and thickness in H. dubia and H. meridiana, different in H. messapia as the scutellar setae are short and thick and the elytral setae long and thin).

FIGURES 24 – 26. Hoplia dubia species group. Comparison between the shape of protoracic tarsi (right leg, ventral view), length uniform. 24, Hoplia dubia (Marina di Vecchiano); 25, H. meridiana (R. N. O. Bosco Pantano di Policoro); 26, H. messapia (Cesine, Le Vernole). A stouter structure, with broader tarsomeres and claw, is evident in H. meridiana (courtesy of Daniele Baiocchi and Lara Gallina).

FIGURES 32 – 33. Hoplia meridiana in nature. 32, male on an ear of grass, Marina di Pisticci, mouth of Cavone stream, 29. IV. 1999; 33, habitat in Policoro (1. V. 2016, courtesy of Giuseppe Cancelliere).