Hoplia (Hoplia) dubia ( Rossi, 1792 )

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 : 204-206

Hoplia (Hoplia) dubia ( Rossi, 1792)

( Figs. 1–3 , 12–13 , 18–19 , 24 , 28–30 )

Search for the type series. Hoplia dubia was cited with the incorrect date of 1790 in monographs and catalogs ( Luigioni 1929; Porta 1932; Baraud 1992; Smetana 2006; Bezděk 2016) and various faunistic papers (e.g.: Mariani 1959; Carpaneto & Piattella 1995; Gobbi & Piattella 2008), but was actually described by Rossi in 1792 (1792: 11, as Melolontha dubia ) based on an unspecified number of specimens. The collection of P. Rossi is believed to have first passed to Federico Sanvitale ( Conci & Poggi 1996). After the death of Sanvitale (in 1819), his entomological collection was acquired by Giorgio Jan ( Adorni 1840; Conci 1967), whose collection contributed to the initial nucleus of what is now the Museo di Storia Naturale di Milano ( Conci 1967). Unfortunately, Jan’s entomological collections were completely destroyed either in 1927 ( Conci & Poggi 1996) or in 1943, during World War II ( Goidanich 1975), therefore the Milano Museum do not still house any specimens originating from Rossi's collection.

However, before the foundation of Milano museum, Jan and his associated G. de Cristoforis lived as free-lance scientists, also selling duplicates of their collections ( Goidanich 1975). Through the sale of duplicates, at least a part of the Rossi and/or Sanvitale material is believed to have been passed to J. Hellwig, whose collection is now preserved in the Zoological Museum of Berlin ( Horn & Kahle 1935 –1937). Even in this institute, however, materials of Rossi seem to be completely missing ( Conci 1975), and a recent survey confirmed that there are no specimens identifiable as being syntypes of H. dubia (Joachim Williers, personal communication to M.U., September 2012).

Therefore, the type series is considered lost, and the designation of a neotype is deemed to be necessary.

Correct identification of the taxon. In spite of the loss of the type specimens, the original description of Hoplia dubia allows its reliable identification among the species of Hoplia occurring in the Italian region once known as “Etruria”, which is the type locality. Here, besides H. dubia , also H. (Decamera) fiorii (D’Amore Fracassi, 1906) , H. argentea (Poda, 1761) , H. brunnipes Bonelli, 1812 , H. maremmana Leo, Liberto, Rattu, & Sechi, 2010 , and H. minuta (Panzer, 1789) are recorded. Fundamental diagnostic characters mentioned by Rossi in the description of H. dubia are: black integuments with testaceous elytra, body covered by silver-green scales, and body covered by dense light-grey setae, longer on head and prothorax. The combination of these characters will exclude all the mentioned taxa but one, which is confidently confirmed to be the true H. dubia . Hoplia maremmana , recently described, was sometimes misidentified in collections as H. dubia , but the short pubescence of the body fits by no means with the long, dense grey setae described by Rossi (1792). In addition, the ranges of the new species H. messapia and H. meridiana do not encompass "Etruria", so these species cannot figure as candidates matching the historical H. dubia .

Type locality. Marina di Vecchiano, Pisa (it was "Etruria" before the designation of the neotype). Specimens examined. A total of 182♂, 6♀ . Neotype (here designated): Italy, Toscana, Marina di Vecchiano (PI), 40.804, 10.265, 5–7.V.2012, leg. M. Uliana (♂, MSNVE) . Other specimens: see Table 2. Integrative and comparative description. For variable characters, the character state of the neotype is between square brackets.

Male. Habitus as in Figs. 1, 3 , 28–30 .

Size. Smaller than the other two species. PBL: 5.7–6.3 mm [5.9], average 6.0 mm; TBL: 7.1–8.0 mm [7.2], average: 7.7 mm; MBW: 3.4–3.9 mm [3.6], average 3.7 mm.

Color. Specimens with black elytra not observed; darkening along suture more marked than in the other two species.

Scales ( Figs. 12–13 ). Shape: on the entire body, more elongate than in the other two species. On the head, if present, thin, bristle-like. On pronotum and scutellum narrowly elliptical to slenderly lanceolate. On elytra elliptical or drop-shaped, on average less elongate than those of pronotum and of pygidium. On pygidium similar to that of pronotum. Color: on head and pronotum nacreous, mostly with pale hues of yellow, green, or pink, less commonly cyan; color of pronotum uniform [as in neotype] or without noticeable variations across the entire surface. On elytra, similar to pronotum along a narrow basal stripe and sometimes the suture [as in neotype], on the rest of the surface yellow or ochre [ochre], more dull. On propygidium, pygidium, ventral side and legs, similar to pronotum. Color in general paler than in H. meridiana and H. messapia . Arrangement: distinctly raised from the integument. On head, absent to very scarce [absent]. On pronotum, two "whirls" are present along the base, at about two-thirds of the distance from the medial line to the posterior angles, with some scales directed forward present along the edge. On elytra, well spaced: in the discal area the transversal distance between two scales roughly 1–2 times the width of one scale.

Setae. In general, longer than H. meridiana and similar to H. messapia (except scutellum). Pronotum setae long on entire surface ( Figs. 3 , 12 ), the longest about 0.4–0.5x the length of the pronotum and 1.2–1.3x the width of scutellum. Length quite uniform across the surface, except a small medial area in the basal third, where setae although mixed in length are on average shorter. This area bears anyway setae almost as long as on the rest of pronotum. Scutellum with setae long and thin, hair-like, similar to those along the base of the pronotum and of the elytra, although on average shorter, measuring about 0.5x the length of the scutellum ( Figs. 18–19 ). Elytral setae hair-like, sparsely mixed in length, long setae present: setae measuring about 1.5–7 times the length of a scale.

Morphology. Clypeus about 2.6–3.1 [2.8] times wider than long (average: 2.7). Sides of pronotum slightly and regularly curved to almost straight, not noticeably angulose. Sutural region of elytra, compared to the rest of the surface, raised, with "swollen" look. Pygidium W/L = 1.23. First antennomere poorly and evenly expanded, apical width about twice the width of the funicle. Protibia, on average, slightly narrower than in the other two species. With particular reference to H. meridiana , teeth sharper, the basal tooth more protruding and acute. Protarsomere slender, similar to that of H. messapia ( Fig. 24 ).

Female. Habitus as in Fig 2 .

Color. Tarsi light brown to dark brown. Specimens with lighter tibiae or femora not observed.

Scales. Color not different from that of the male, including the pronotum.

Morphology. Elytra with shape similar to that of the male. Pygidium more convex than in males, ratio W/L: 1.16.

Distribution. Hoplia dubia is known for the coast of northern Tuscany, between Viareggio and Gombo, west of Pisa. The species is not recorded south of the Arno River, although it may be present in the small fragments of suitable habitat between there and Livorno ( Fig. 27 ).

Figures

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

FIGURES 1 – 3. Habitus of Hoplia dubia in dorsal and lateral view. 1, 3: male; 2: female. All from Marina di Vecchiano.

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 28 – 31. Hoplia dubia in nature from Marina di Vecchiano, 5. V. 2012. 28 – 29, male in activity on a dry stalk; 30, male sheltered among Juniperus fronds after a storm; 31, habitat of the species.