A new enigmatic species of broad-nosed weevil endemic to Brazil and its phylogenetic placement within the tribe Naupactini (Coleoptera: Curculionidae: Entiminae)

A new species of Naupactini (Curculionidae: Entiminae) endemic to Brazil, Espírito Santo and Minas Gerais states, is herein described. It resembles the monotypic genus Hadropus Schoenherr in its general appearance, particularly in the shape of the elytra, and the color of the vestiture, but the results of a cladistics analysis herein conducted suggest that it belongs to the genus Stenocyphus Marshall. This genus ranges in São Paulo, Rio de Janeiro and Espírito Santo, mainly in the Atlantic forest of Brazil, and includes three other species. Stenocyphus costae sp. nov., distinguishes from the remaining species of Stenocyphus by the green iridescent scaly vestiture, having long stiff setae on the two pairs of elytral tubercles; the more slender rostrum; the shorter antennae; the convex disc of the pronotum; and the shorter and broader elytra. This paper includes a cladogram of the Naupactini genera showing the phylogenetic position of the new species, its complete description, photographs of male and female habitus, line drawings of genitalia of both sexes, and a key of the Stenocyphus species. Key-Words. Hadropus; Neotropical region; South America; Stenocyphus.


INTRODUCTION
The Neotropical genera Hadropus Schoenherr, 1826 and Stenocyphus Marshall, 1922 (Curculionidae, Entiminae, Naupactini) share several morphological characters, such as the presence of elytral tubercles and the disc of the elytra elevated towards the beginning of the declivity (humped elytra); the vestiture composed of scales and coarse setae; the tibiae lacking rows of denticles along the inner margin or with minute denticles; and the corbels of the metatibiae well-developed, covered with scales or scale-like setae. Hadropus is a monotypic genus that ranges in Paraguay and Brazil, mainly in the Chacoan and Parana subregions (del Río & Lanteri, 2011), and Stenocyphus is endemic to Brazil, and is mainly distributed along the Atlantic forest, from São Paulo to Espírito Santo (del Río & Lanteri, 2013). Mixed in the series of Hadropus albiceris Germar, we found some specimens which are similar to this species in the characters of the vestiture and shape of the elytra, but differentiate in some diagnostic characters at generic level, such as those of the rostrum and shape of the spermatheca (see del Río & Lanteri, 2011). We concluded that these specimens correspond to a new species, and in order to test its generic position we undertook a cladistics analysis based on morphological characters.
The objectives of this contribution are to describe the new species, to illustrate its diagnostic characters, and to analyze its phylogenetic position within the tree of the Naupactini, to decide about to its correct generic placement.

MATERIAL AND METHODS
Specimens of the new species are very scarce in entomological collections, and they would be rare in nature. This study was based upon the examination of specimens borrowed from the fol- Dissections of female and male genitalia were made according to standard entomological techniques. Characters of the genitalia were drawn using a camera lucida adapted to a stereoscopic microscope Nikon SMZ800. Measurements were taken with an ocular micrometer attached to this microscope. The abbreviations used in the description are as follows: L = maximum length; W = maximum width; WR = width of rostrum measured across apex (excluding scrobes); WF = width of forehead between anterior margins of eyes.
The key for the species of Stenocyphus was expanded from that of del Río & Lanteri (2013).

Phylogenetic analysis
The morphological characters and character states used for this phylogenetic analysis were listed in Lanteri & del Río (2017) ( Table S1). The list consisted of 100 discrete morphological characters of the adults, including 78 from the external morphology and 22 from the female and male genitalia.
A data matrix herein analyzed includes 76 terminal taxa (72 for the ingroup plus four outgroups) and 100 morphological characters (Table S2). Character states unknown were scored with "?" and treated as missing data (Maddison, 1993). All characters were treated as non-additive and were analyzed under equal and implied weights (K = 45).
Searches were conducted using the "traditional search" algorithm of TNT (Goloboff & Catalano, 2016), with 300 random addition sequences, Tree Bisection and Reconnection (TBR) branch swapping, holding 20 trees during each replication. Clade stability was evaluated with 1000 replication Bootstrap (BT) (Felseinstein, 1985). We provide the total length (L), the consistency index (CI) (Kluge & Farris, 1969) and the retention index (RI) (Farris, 1989) of the most parsimonious trees (MP tree), calculated excluding the uninformative characters. Since more than one most parsimonious tree was obtained, we calculated a strict consensus tree among them (Goloboff & Farris, 2001).

Cladistic analysis
The heuristic search under equal weights yielded 35 equally parsimonious trees (L = 816 steps, CI = 0.21, RI = 0.54). In the consensus tree ( Fig. 1), same as in the analysis under implied weights (k = 45), the new species is recovered in a clade including the species of Stenocyphus and Neoerycideus Hustache, 1938, mainly supported by the elytral disc ascending towards the beginning of the declivity (= humped) (char. 53.1) and the denticles of the inner margin of tibiae absent or minute (char. 70.0). The new species form a clade with the other three species of Stenocyphus (BT: 36), mainly supported by the presence of lateral rostral carinae (char. 11.1); gular angle slightly obtuse (char. 27.1); disc of pronotum with irregular foveae or large punctures (char. 48.1); elytra with tubercles on disc and declivity (char. 57.1); apex of median lobe of aedeagus rounded (char. 96.2) and endophallus of penis with flagellum (char. 98.1).
The new species is not related to Hadropus, which is included in another clade of Naupactini where members also have humped elytra (see Fig. 1).

Pronotum (Figs. 2C-D):
As long as wide to slightly transversal (L/W: 1.05-1.25), sides divergent towards anterior ⅓ and almost subparallel on posterior ⅔, maximum width on anterior ⅓; disc slightly convex and elevated from base to apex, disc with irregular foveae and not well-defined median groove; anterior margin slightly curved anteriad; base bisinuate, with postero-lateral angles projected backwards.
Legs: Procoxae contiguous, 2× closer to anterior margin than to posterior margin of prosternum; protibiae strongly curved onwards, without denticles on inner face, and with erect thick setae on inner and outer face; pro-and mesotibiae with mucro and metatibiae without mucro; corbels of metatibiae well developed, covered with scale-like setae; dorsal comb slightly shorter than distal comb; tarsomere 2 as long as wide; tarsal claws free.

Etymology:
The species is named in honor of Dr. Cleide Costa, the outstanding Brazilian Coleoptera specialist.

DISCUSSION
The new species is very similar in appearance to that of the genus Hadropus, but besides this superficial similarity it is not related to this genus (see results of the cladistic analysis). In the single species of Hadropus the rostrum is much shorter and wider, and lacks lateral carina; the epistome is more differentiated from the post-rostrum; the spermatheca has a particular shape (without collum, with broad and prominent ramus); and the penis lacks flagellum. All these characters are important to separate genera in the tribe Naupactini.
On the contrary, Stenocyphus costae sp. nov., shares most synapomorphies of Stenocyphus (see results of the cladistic analysis) and has a particular combination of features that allow distinction from the other species of this genus: e.g., scape not reaching hind margin of eye (char. 31.0); club oval, very short (length/width 2.0 to 2.25×) (char. 37.0); pronotum convex (char. 44.1), with postero-lateral angles projected (char. 45.1); procoxae twice as close to anterior margin than to posterior margin of prosternum (char. 65.2); and apodeme of sternite VIII less than 2× as long as plate (char. 80.0).
With the inclusion of the new species in Stenocyphus the distribution of this genus extends western to the state of Minas Gerais. Consequently, this genus does not occur only in the Atlantic Forest (oriental slopes of the coastal hills of Brazil, characterized by a pluvial forest of trees of 30-40 meters, with a lower stratum rich in palms, lianas and epiphytes), but also in the transition area with the Cerrado (largest savanna forest, with open forest having low trees, shrubs, a stratum of herbs rich in Poaceae and Fabaceae). The Serra de Caraça (Minas Gerais), where the species S. costae sp. nov., coexists with Hadropus albiceris, is a unique area of great biological diversity, as it covers a variety of habitats, including montane forest, cloud forest, shrubby montane savannas and high-altitude grasslands. It contains species endemic to the Cerrado (particularly those restricted to campos rupestres in the Espinhaço mountain range), as well as Atlantic Forest endemics. This is an area of high conservation priority in Minas Gerais, where the flora and fauna are currently threatened of extinction (Costa et al., 1998).
It would be very important to collect more extensively in this area of Brazil to find out the accurate distribution of Stenocyphus and its possible intraspecific variation.