Tropirhinus palpebratus Franz & Zhang [FZ2017]

Franz, Nico & Zhang, Guanyang, 2017, Three new species of entimine weevils in Early Miocene amber from the Dominican Republic (Coleoptera: Curculionidae), Biodiversity Data Journal 5, pp. 10469-10469 : 10469

Tropirhinus palpebratus Franz & Zhang [FZ2017] sp. n.

Materials

Type status: Holotype. Occurrence: catalogNumber: ARTSYS0000270 ; recordNumber: Woodruff #9768; recordedBy: R.E. Woodruff; individualCount: 1; sex: Female; lifeStage: Adult; preparations: Amber inclusion; disposition: USNM, on loan; otherCatalogNumbers: USNM505319; occurrenceID: 266d8782-5bf5-4763-b3fa-ea057a3fc55a; Taxon: scientificName: Tropirhinuspalpebratus; nameAccordingTo: Franz & Zhang 2017; namePublishedIn: Franz, N.M. & G. Zhang. 2017. Three new species of entimine weevils in Early Miocene amber from the Dominican Republic (Coleoptera: Curculionidae). Biodiversity Data Journal.; kingdom: Animalia; phylum: Arthropoda; class: Insecta; order: Coleoptera; family: Curculionidae; scientificNameAuthorship: Franz & Zhang, 2017; Location: country: Dominican Republic; stateProvince: La Vega; locality: Unknown mine ; decimalLatitude: 19; decimalLongitude: -70.666667; geodeticDatum: WGS84; georeferencedBy: N.M. Franz; georeferenceSources: Google Earth; georeferenceVerificationStatus: Verfied by Curator; Identification: identifiedBy: N.M. Franz & G. Zhang; dateIdentified: 01/15/2017; identificationReferences: Franz, N.M. & G. Zhang. 2017. Three new species of entimine weevils in Early Miocene amber from the Dominican Republic (Coleoptera: Curculionidae). Biodiversity Data Journal.; Event: verbatimEventDate: Early Miocene, Burdigalian; habitat: Amber inclusion, Early Miocene (Burdigalian); Record Level: modified: 24/01/2017 18:31; rights: http://creativecommons.org/publicdomain/zero/1.0/; rightsHolder: United States National Museum; bibliographicCitation: Franz, N.M. & G. Zhang. 2017. Three new species of entimine weevils in Early Miocene amber from the Dominican Republic (Coleoptera: Curculionidae). Biodiversity Data Journal.; institutionID: USNM; collectionID: 0acac5fe-f0ec-4d9f-82f8-0dbb74888de2; institutionCode: SCAN; collectionCode: ARTSYS; ownerInstitutionCode: USNM; basisOfRecord: FossilSpecimen; source: http://symbiota4.acis.ufl.edu/scan/portal/collections/individual/index.php?occid=25836760

Description

Female - habitus (Fig. 2). Length 8.6 mm, width 3.6 mm; shape in dorsal view oval to elongate, length/width ratio 2.4, widest near mid region of elytra; shape in lateral view elongate to pyriform. Integument uniformly dark brown to black; surface sculpture punctate, subcircular punctures largest on pronotum; integument entirely and homogenously covered with setae and scales, each apparently pale yellow in color, with no maculae apparent, darker and with metallic aspects on the legs; setae short and linear, densely and regularly arranged, directed posteriad, appressed, scales very small, subcircular, overlapping.

Mouthparts. Mandibles equilateral, with 3-5 coarse and several finer setae; mandibular scar positioned apicolaterally, projected. Maxillae not apparent, covered by labium (however, the maxillary palps are 3-segmented in extant members of Tropirhinus Schoenherr [FZ2017]). Labium with prementum cordate, equilateral; labial palps apparently 3-segmented.

Rostrum. Length 1.3 mm, rostral/pronotal length ratio 0.8, rostral length/width ratio 1.1. Rostrum in dorsal view equilateral to rectangular, dorsolateral margins nearly straight and distance between them anteriorly gradually widening, anterodorsal margin with a distinct, narrow, V-shaped mesal emargination; epistoma with nasal plate (see Vaurie 1963) weakly developed, angled in relation to posterior rostrum region, slightly depressed, V-shaped carina absent; dorsal surface with a median, wide, glabrate, weakly projected carina (or elevation), extending from posterior margin of epistoma to mid point between eyes. Rostrum in lateral view slightly arcuate, tumescent in dorsal mid region; scrobe lateral, slightly arcuate, posteriorly directed ventrad of eye, though also terminating anteriad of eye; antennal insertion near anterior 1/4. Antennae 11-segmented; scape slender, slightly arcuate, extending to posterior margin of eye, and passing ventrad of eye (in idealized position); funicle 7-segmented, funicular antennomeres elongate, weakly clavate, I and II similar in length, III to VII shorter, and increasingly so towards the apex; club 3-segmented, narrowly elongate, similar in length to funicular antennomeres V-VII.

Head. Eyes large, globular (strongly roundly protruded), dorsolaterally positioned, separated by distance similar to anterior-to-posterior length of each eye; outline in lateral profile elliptical (horizontally more extended), ventral margin less rounded.

Thorax. Pronotum in dorsal view equilateral to transverse, weakly convex, length/width ratio 0.85, pronotal/elytral length ratio 0.25; widest near posterior 1/3, lateral margins continuously rounded; surface punctate, with a wide, elliptical median sulcus (or impression) extending along anterior 1/2 of pronotum. Pronotum in lateral view equilateral; anterolateral margins with a small postocular lobe, and dorsad thereof with a tuft of 4-6 slightly longer, anteriorly directed setae ("postocular vibrissae", except these are not projecting from the postocular lobe but are dorsad of it). Scutellum exposed by elytra, small, escudate, posterior margins rounded. Epipleura with mespisternum triangular; mesepimeron dorsally oblique truncate; metepisternum linear, anteriorly widened; metepimeron entirely covered by elytron. Prothoracic ventrite with anterior margin widely emarginate; proxocal cavities positioned near mid point, contiguous. Mesothoracic ventrite with plumose-scopiform scales; mesocoxal cavities separeated by distance 1/3 as wide as each mesocoxal cavity. Metathoracic ventrite with median sulcus present as a large, transverse fovea positioned anteriad of posterior margin; metacoxal cavities separated by distance similar to width of each metacoxal cavity. Metendosternite not observed.

Legs. Prothoracic and metathoracic legs each slightly longer than mesothoracic legs (mesofemora shortest in comparison), generally similar to those of Diaprepes abbreviatus sec. Franz (2010a). Profemoral/pronotal length ratio 1.3; profemur ventrally inermous. Protibial/profemoral length ratio 1.2; protibia apically angulate-arcuate, width similar throughout; anteromesal margin with 5-8 small, triangular teeth, each tooth distally with 1 brownish, spiniform seta; protibial apex with anterior margin truncate, setal comb absent, promucro similar in length to protarsal claw; protarsus swith tarsomeres I and II similar in length, each slightly shorter than III which in turn is shorter than V; protarsal claws paired, separate, simple. Mesotibiae and metatibiae nearly straight, apically slightly expanded and obliquely rounded; metatibial apex with a narrowly elliptical outer bevel ("corbel enclosed"; see Thompson 1992).

Elytra. Length/width ratio 1.8; widest near mid region; anterior margins jointly wider than posterior margin of pronotum, slightly sinuate; humeri present, rounded; lateral margins continously rounded, nearly straight in mid region, more strongly converging in along posterior 1/4; posterior edges each with a short, narrowly triangular, ante-apical projection. Elytra in lateral view with dorsal outline subplane along anterior 1/2, thereafter continuously rounded (hence declivity convex), less so along posterior 1/8. Elytra with striae I-IX complete, stria X only apparent along anterior and posterior 1/3; striae similar in width to intervals; punctures separated by distance similar to width of each puncture; intervals slightly and roundly elevated; pale-colored scales and setae covering elytra homogenously, with no maculae apparent.

Wings. Present, yet not observed (covered by elytra).

Abdomen. Venter with segments III and IV jointed (see Thompson 1992 for segment homology), similar in length, and separated by sinuate suture; V-VII separate; V and VI jointly slightly shorter than IV, posterior margins elevated-projected; VII similar in length to IV, triangular, posteriorly narrowly truncate. Pygidium posteriorly narrowly rounded, covered by elytra.

Terminalia. Not unambiguously observable; however, the stylus and setae of the left coxite appear to project from the terminal opening, which is indicative of the female identity of the specimen (along witht the triangular ventral segment VII).

Male. Unknown.

Diagnosis

Generic placement. Tropirhinus palpebratus [FZ2017] shares with (e.g.) Tropirhinus elegans ( Guérin 1847) sec. Franz (2012) numerous phylogenetically informative traits inferred in Franz (2012) that substantiate this generic placement (see also Tables 1, 2, 3, 4, 5, 6). They include: 9(1): rostrum in lateral profile slightly arched and tumescent in mid region of dorsal surface; 16(1): rostrum dorsally mono- or tricarinate; 17(0): rostrum monocarinate, with one median, wide and rounded carina; 23(1): scrobe (of antenna) passing ventrad of eye in lateral profile; 31(0): head-rostrum transition in lateral profile continuous or only slightly angulate; 32(0): head in dorsal profile without a conspicuous postocular constriction; 34(0): head without an anteocular invagination; 58(2): metatibial apex with an outer bevel ("corbel enclosed"; see Thompson 1992); 67(1): posterior margins of elytra with an ante-apical, narrowly triangular projection; and 83(0): wings fully developed. The most parsimonious reconstructions furthermore postulates two wing properties that cannot be obversed in this amber inclusion, viz. 84(1): wings in proximal third with at least one patch of small, densely arranged denticles; and 85(2): patches of denticles in proximal region of wings distributed in rows along R (vein). This combination of character states is shared only between Tropirhinus palpebratus [FZ2017] and Tropirhinus elegans sec. Franz (2012) as coded in that latter analysis, and this correspondence of phylogenetically informative traits is the primary justification for assigning Tropirhinus palpebratus [FZ2017] to Tropirhinus [FZ2017].

We thereby assign to Tropirhinus [FZ2017] an expanded circumscription in comparison to (e.g.) Tropirhinus sec. O'Brien and Wibmer (1982), whose three members lack a postocular lobe and in turn have variously patterned metallic-colored maculae on the pronotum and elytra (see Guérin-Méneville 1847, Chevrolat 1877, Zhang et al. 2017). These and other apparent differences - e.g., only Tropirhinus novemdecimpunctatus (Fabricius 1781) sec. O'Brien and Wibmer (1982) has strongly protruding eyes - could be emphasized to justify the creation of a new genus-level name for the amber-preversed specimen under study. However, two kinds of considerations caution against this at present (see Vences et al. 2013). First, the characters and states that distinguish Tropirhinus palpebratus [FZ2017] from the other members of Tropirhinus [FZ2017] are frequently homoplasious in this greater lineage of Caribbean entimine weevils (as analyzed in Franz 2012 and Zhang et al. 2017). The presence or absence of a postocular lobe, or of postocular vibrissae, are variable traits within Diaprepes Schoenherr [FZ2017] (see also O'Brien and Kovarik 2001, Franz 2012). Metallic coloration patterns are often variable within and among the recognized members of (e.g.) Exophthalmus Schoenherr 1823 sec. Morrone (1999). Accordingly, our expanded genus-level concept Tropirhinus [FZ2017] entails primarily characters and states that appear to be phylogenetically 'labile' at low taxonomic levels. We consider this acceptable. Second, creating a new genus-level name for this specimen makes no tangible contribution to resolving the taxonomic identity of extant and closely related lineages, including members of Compsoricus Franz 2012 sec. Franz (2012), Pachnaeus Schoenherr 1826 sec. O'Brien and Wibmer (1982), Tetrabothynus Labram and Imhoff 1852 sec. O'Brien and Wibmer (1982), and the likely taxonomically misnamed Exophthalmus quindecimpunctatus (Olivier 1807) sec. Franz (2012) (therein incorrectly spelled) and Exophthalmus roseipes (Chevrolat 1876) sec. Franz (2012). The combination of an abundance of available genus-level names and still inadequate knowledge of the species-level diversity and phylogenetic relationships of the various aforementioned lineages (see also Zhang et al. 2017) makes it less appealing to create yet another genus-level name at this juncture.

Franz (2012) assigned Tropirhinus sec. Franz (2012) to the tribe Geonemini Gistel 1856 [non-focal], and this placement is not under taxonomic scrutiny here.

Differential diagnosis. Tropirhinus palpebratus [FZ2017], in addition to being extinct and recorded from Dominican amber, is readily distinguished from the extant members of Tropirhinus [FZ2017] by the presence of a small, postocular lobe (with a setal patch ventral thereof) and absence of metallic-colored pronotal and elytral maculae. Moreover, the eyes of Tropirhinus palpebratus [FZ2017] are more globular and protruded than those of Tropirhinus elegans sec. Franz (2012) and Tropirhinus tredecimpunctutatus ( Guérin 1847) sec. O'Brien and Wibmer (1982), although those of Tropirhinus novemdecimpunctatus sec. O'Brien and Wibmer (1982) are similarly globular (see Chevrolat 1877; in particular plate IV, figure 4 therein). Lastly, Tropirhinus palpebratus [FZ2017] shows a smaller, only anteriorly extending pronotal sulcus, in contrast with a larger and more posteriorly extending pronotal impression that is flanked laterally by obtuse, rounded elevations, as present in other members of Tropirhinus [FZ2017]. Members of Pachnaeus sec. O'Brien and Wibmer (1982) have a wider rostrum and lack the posterior elytral projections, whereas those of Tetrabothynus sec. O'Brien and Wibmer (1982) have a postocular head constriction. Other close relatives (see Franz 2012) have distinctly different pronotal and elytral sculpture and coloration patterns; e.g. Compsoricus sec. Franz (2012) has large longitudinal carinae and Exophthalmus quindecimpunctatus sec. Franz (2012) has green metallic scales interspersed with distinct black maculae.

Etymology

The epithet - "eyelid, wink" ( Brown 1956) - refers to the combination of the postocular lobe and the setal patch located ventral thereof - a set of traits that uniquely corresponds to Tropirhinus palpebratus [FZ2017] in relation to close relatives.

Distribution

Tropirhinus palpebratus [FZ2017] is known only from the examined Dominican amber inclusion ("USNM505319"; see Material) of the Burdigalian time period. The specific mine of origin for this inclusion is unknown.

Ecology

Unknown.