Taxonomic revision of the genus Stenocyphus Marshall (Coleoptera, Curculionidae) from Brazil

Abstract Stenocyphus Marshall, 1922 (Entiminae, Naupactini) includes three species: the type species S. bituberosus (Gyllenhal, 1833), S. tuberculatus (Hustache, 1938), comb. n. herein transferred from Neoericydeus Hustache, 1938, and S. sextuberosus sp. n. The genus is endemic to the Atlantic forests of the states of Espirito Santo, Rio de Janeiro and São Paulo, Brazil andis mainly characterized by the presence of humped elytra bearing large conical tubercles on the intervals 5, or 3 and 5, or 3, 5 and 7. It shares some external morphological characters with Hadropus Schoenherr, 1826 and the Brazilian species of Cyrtomon Schoenherr 1823, but its phylogenetic position is uncertain. Herein we provide a diagnostic key to separate Stenocyphus from those genera, generic and species redescriptions or descriptions, a key to species, habitus photographs, line drawings of genitalia, and a discussion of the patterns of elytral tubercles in unrelated genera of Neotropical broad-nosed weevils.


Introduction
Stenocyphus was described by Marshall (1922) as a monotypic genus of Entiminae Schoenherr, 1823, tribe Naupactini Gistel, 1848, based on the type species Cyphus bituberosus Gyllenhal, 1833. It is endemic to Brazil, where it occurs in the Atlantic province of the Neotropical region sensu Morrone (2006). Although it was included in diagnostic keys of Naupactini by Emden (1944) and Hustache (1947), Stenocyphus was never revised.
The main objective of this contribution is to redescribe Stenocyphus, as well as its type species S. bituberosus (Gyllenhal), to describe a new species, S. sextuberosus, and to accommodate one species transferred from Neoericydeus Hustache, 1938, N. tuberculatus (Hustache, 1938, establishing the new combination Stenocyphus tuberculatus. We provide habitus photographs of the three species, drawings of female and male genitalia, and a discussion on probable generic relationships and development of elytral tubercles in other Neotropical Entiminae.

Materials and methods
Specimens of Stenocyphus are scarce in entomological collections throughout the world and probably rare in nature. We have examined material from the following institutions:

AMNH
American Museum of Natural History, New York, USA. Lee Herman. BMNH Natural History Museum, British Museum of Natural History. Chrystopher Lyal. Dissections were made according to standard entomological techniques. Photographs and drawings were done with a digital camera (Micrometrics 391CU, 3.2 m) and a camera lucida attached to a stereoscopic microscope Nikon SMZ1000. Measurements were taken with an ocular micrometer. Measurements, with their abbreviations are as follows: LB, total body length, measured along midline, from apex of rostrum to apex of elytra; LS, standard body length, measured along midline, from anterior margin of pronotum to elytral apex. LA, maximum length of antenna; LC, maximum length of club; WC, maximum width of club; LR, length of rostrum; WF, width of forehead between anterior margin of eyes; WR, width of rostrum measured across apex (excluding scrobes); LP, maximum length of pronotum; WP, maximum width of pronotum; LE, maximum length of elytra; WE, maximum width of elytra. Diagnosis. Species medium-sized (LB: 10-16 mm long; LS: 8.4-13.0 mm long); body elongate, slender; integument densely covered with dull whitish, cream, or tan vestiture, composed of overlapping scales and scattered seta-like scales or setae (Figs 1-6). Rostrum short, with distinct lateral carinae (Fig 7). Antennae slender, setose, moderately long; scape exceeding posterior margin of eyes. Pronotum slightly truncate-conical, impressed on disc and flanks. Elytra humped, with strongly bisinuate base and prominent humeri, bearing conical tubercles on elytral intervals 5, or 3 and 5, or 3, 5 and 7 (Figs 1-6). Metatibial apex with broad, squamose corbel, and apical comb about 2× longer than dorsal comb. Aedeagus with long, curled flagellum.
Integument black, densely covered with dull whitish, cream or tan vestiture; scales subcircular and striate; seta-like scales pale, short, decumbent on rostrum, pronotum and elytra, and moderately long on elytral tubercles, venter and legs (longer and denser on inner and outer face of tibiae).
Distribution. Stenocyphus is distributed along the coastal hills of eastern Brazil, in Espirito Santo, Rio de Janeiro and São Paulo states. This area corresponds to the Atlantic province of the Neotropical region sensu Cabrera and Willink (1980), or Brazilian Atlantic Forest according to the biogeographic scheme of Morrone (2002Morrone ( , 2006. It is characterized by a pluvial forest of trees of 30-40 meters high, with a lower stratum rich in palms, lianas and epiphytes.
Male genitalia. Penis (Figs 23-24) about 1.45× as long as temones. Endophallus with two lateral long sclerites and a flagellum.  Figs 2,5,9,12,15,18,21,25,26 Diagnosis. The new species Stenocyphus sextuberosus is easily distinguished by the presence of three pairs of tubercles on the elytral disc, two on interval 3 and one on interval 5. The largest pair of tubercles is slightly directed backwards, placed on the posterior 2/3 of interval 3, and followed by a small one; the tubercle on interval 5 is large but rounded and is placed near the declivity. The other species of Stenocyphus bear two (S. bituberosus) or more than six elytral tubercles (S. tuberculatus). Stenocyphus sextuberosus also differs from the closest species S. bituberosus in the following characters: body slightly smaller, scape of antennae slightly longer, elytra with three pairs of tubercles instead of one pair, intercoxal portion of abdomen slightly broader than cavities of metacoxae, spermatheca more globose and aedeagus flattened towards apex in lateral view. The main differences with S. tuberculatus are in the shape of the scutellar shield (triangular instead of suboval), the presence of mucro and denticles on the protibiae, the absence of rows of setae along sides of the ovipositor, and the shape of the spermatheca (with apex of nodulus shorter, curved towards opening of gland, and indistinct ramus).
Elytra (Figs 2, 5) slender (LE/WE: 1.57; LE/LP: 3.27), with three pairs of tubercles on posterior third, two on interval 3 and one on interval 5, the latter between the other two: first pair on interval 3 large, slightly directed backwards, second pair on interval 3 small, and tubercles on interval 5 large but rounded; humeri slightly prominent; disc flat, slightly elevated towards declivity; punctures of striae deep; intervals slightly wavy except the distinctly elevated and light colored anterior 1/4 of interval 3 and anterior 2/4 of interval 5.
Male genitalia. Penis (Figs 25-26) about 1.5× as long as temones, flattened towards apex in lateral view. Endophallus with spines at proximal end and a flagellum.
Etymology. The name of the new species is an adjective that refers to the six tubercles present on the elytral disc, a distinct character that allows differentiation from the remaining species of Stenocyphus.

Diagnosis.
Stenocyphus tuberculatus is easily distinguished by the presence of three series of conical tubercles along elytral intervals 3, 5 and 7, from base to apex, with the largest tubercles placed near the declivity of interval 3. It also differs from the other two species of Stenocyphus by the following characters: elytral disc with fine, dark, erect setae scattered on posterior 2/3, rostrum almost subparallel-sided; scutellar shield suboval; elytral disc slightly convex and elevated towards declivity, with indistinct punctures of striae; all tibiae with indistinct mucro and denticles; protibiae broad and densely setose; ovipositor with coarse setae along external sides of apical 2/3 of baculi; spermathecae slender, with moderately long nodulus, not curved towards opening of gland. Redescription. LB: female (Figs 3, 6) 16 mm long (LS: 13 mm). Vestiture whitish, except on dorsum of rostrum, head and pronotum which are tan coloured. Elytral disc with fine, dark, erect setae scattered on posterior 2/3. Rostrum (Fig 3) (LR/WR: 1.00) with sides very slightly convergent toward apex (WF/WR: 1.20). Eyes larger than in the other two species; preocular impression strong; prementum subcircular.
Distribution. Brazil, state of Espirito Santo. (Hustache) was originally described in Compsus Schoenherr, 1823 (Entiminae: Eustylini) and transferred to Neoericydeus (Entiminae: Naupactini) by Kuschel (1955). Based on the characters of the rostrum, this species clearly belongs to Naupactini and not to Eustylini, however, we do not agree with its placement in Neoericydeus, a South American genus with three species that needs revision. The type species N. gratiosus Hustache, 1938 lacks elytral tubercles and shows a vestiture of greenish or bluish iridescent scales, interrupted with setose black maculae on the pronotum and elytra, the same as in the genera Ericydeus Pascoe, 1880 and Briarius [Fischer de Waldheim] 1829 (see Lanteri 1995;Lanteri and del Río 2003).

Remarks. Stenocyphus tuberculatus
The characters of N. tuberculatus are typical of Stenocyphus, thus this species is herein transferred to this genus as Stenocyphus tuberculatus. The other two species of Stenocyphus are more similar to each other in most characters, and they lack the rows of setae on each side of the baculi of the ovipositor. Unfortunately, male genitalia could not be studied due to the absence of material.
The Brazilian species of Naupactini distributed in Espirito Santo state are usually strongly differentiated from other congeners ranging in southern distributions (e.g. Rio de Janeiro and São Paulo states). The pattern of morphological differentiation along the Brazilian Atlantic forests seen in Stenocyphus is also present in species of Briarius, Cyrtomon Schoenherr, 1823, Ericydeus and Teratopactus Heller, 1921(Lanteri 1990a, 1995, Lanteri and del Río 2003, del Río et al. 2006.

Discussion
In a preliminary cladogram of the Naupactini genera, Stenocyphus shows an uncertain, position (del Río and Lanteri 2010), however, it is probably related to a group of genera characterized by the presence of humped elytra (disc progressively elevated from the base to the beginning of the elytral declivity) and broad squamose corbels. Several external features resemble the genus Cyrtomon (senior synonym of Cyphus Germar, 1824), particularly those of the type species Cyrtomon gibber (Pallas, 1781). However, the species of Cyrtomon differ as follows: absence of the typical elytral tubercles of Stenocyphus; external surface of the prementum bears long easily visible setae; dorsal comb of the metatibiae is longer than the apical comb; male and female genitalia very different, especially the penis (with typical arrowpointed apex, having one central and two lateral points, and a distinct sclerite in the endophallus), spermatheca (with long, subcylindrical nodulus, well developed ramus, and wide, curled and strongly sclerotized spermathecal duct, same as in Priocyphus Hustache, 1939) (see Lanteri 1990a, b). In Stenocyphus the apex of the penis is rounded and it bears a curled flagellum, the spermathecae have a conical nodulus, indistinct or small ramus, and narrow, membranous spermathecal duct. Moreover, in S. tuberculatus the ovipositor bears a row of setae along each side of the baculi, as in some species of the genera Naupactus Dejean, 1821 and Teratopactus (see del Río et al. 2006). Another Brazilian Naupactini with humped elytra that could be related to Stenocyphus is Hadropus Schoenherr, 1826; however, in this genus the antennae, rostrum and elytra are much shorter, the epistome is very distinct, and the spermatheca has a characteristic shape (with indistinct nodulus and strongly prominent ramus) (see del Río and Lanteri 2011) similar to that of Enoplopactus Heller, 1921 (see Lanteri 1990c).
In the same area of the elytra where Stenocyphus has the typical tubercles (intervals 3, 5 and 7, near declivity), Cyrtomon gibber has a pair of impressions, and the single species of Hadropus, H. albiceris (Germar, 1824) shows distinct tufts of erect, dark setae. Something similar has been observed in species of Briarius and Ericydeus (Lanteri 1995;Lanteri and del Río 2003).
The presence of tubercles on the elytral disc is a distinct feature of other Neotropical Entiminae that bear humped elytra, lacking close relationship with Stenocyphus. For example Compsus bituberculatus Kirsch, 1889 (Eustylini Lacordaire, 1863) shows a single pair of tubercles as does Stenocyphus bituberosus. Within the tribe Naupactini the elytral tubercles are also present in the Central American monotypic genus Tetragonomus Champion, 1911(type species T. tuberosus Champion, 1911  Furth (USNM) for checking the English language, and to the "Consejo Nacional de Investigaciones Científicas y Técnicas" (CONICET) of Argentina (PIP 1272) and the "Agencia Nacional de Promoción Científica y Tecnológica", for its continuous financial support.