Albicar contriti, 2014

Peris, David, Davis, Steven R., Engel, Michael S. & Delclòs, Xavier, 2014, An evolutionary history embedded in amber: reflection of the Mesozoic shift in weevil-dominated (Coleoptera: Curculionoidea) faunas, Zoological Journal of the Linnean Society 171 (3), pp. 534-553 : 541-543

ALBICAR CONTRITI PERIS, DAVIS, ENGEL ET DELCLÒS SP. NOV. ( FIG. 4 )

Etymology

The specific epithet contriti is Latin for ‘crushed’, referencing the distorted state of the holotype.

Holotype

CES–432, from the El Soplao amber outcrop, housed at the Institutional Collection located in the laboratory of the El Soplao Cave. The holotype is a completely preserved specimen, compressed laterally and distorted mostly on the pronotum and head, as visible in the dorsal aspect ( Fig. 4A ). The piece of amber in which the specimen is embedded has low transparency and therefore it is difficult to observe ventral characters; however, the lateral and dorsal aspects are clearly accessible.

Type locality

The El Soplao site, in the municipality of Celis (Cantabria, Spain). The piece was found in the Las Peñosas Formation, early Albian in age ( Najarro et al., 2009).

Diagnosis

As for the genus (vide supra). Description

Body length 2.3 mm (as preserved, without the rostrum length), maximum body width 0.7 mm (but the fossil is clearly compressed).

Head slightly narrower than pronotum; constricted behind compound eyes, but strongly dilated behind constriction ( Fig. 4B ). Compound eyes large, lateral, rounded, rather coarsely faceted, strongly convex and protruding; compound eyes slightly separated by approximately width of antennal funicular article, contiguous to base of rostrum. Rostrum 10.6 times as long as wide in apex, 7.1 times as long as wide in middle and at base, 1.5 times as long as prothorax (measured in lateral habitus), narrow and broadly curved to apex. Mandibles not protruding, apparently neither exodont nor inclined. Antennae inserted laterally at approximate basal one-third ( Fig. 4B ); antennae apparently reaching elytra when directed posteriorly; antennal funicle with seven articles, not geniculate despite elongate scape; all antennomeres except apicalmost with conspicuous lateral setae. Scape long, 7.0 times as long as wide in apex, forming longest article, extending to anterior margin of compound eyes, 2.0 times length of pedicel and narrower than it; pedicel (funicular article 1) narrower at base and wider subapically, 3.4 times as long as wide in apex; funicular articles 2 and 3 straight, similar in length and narrower than pedicel; funicular articles 4 to 6 constricted close to basal portion; funicular article 7 only observed basally, similar in shape to anterior ones and slightly wider; club article 3 widest, similar in length to pedicel, apically pointed.

Prothorax length 0.56 mm. Base of pronotum narrower than elytra (despite marked specimen compression). Anterior angles of prothorax rounded. Procoxal cavities situated close to middle of prosternum; both pro- and mesocoxae very convex, protuberant.

Elytra length 1.6 mm, approximately 2.8 times as long as pronotum; probably more than 2.0 times as long as wide in middle; punctures and striae indiscernible, although apparently with a sparse scattering of small punctures at most; sutural striole absent; setae largely absent; rounded apically.

All legs similar in length; trochanters short, femora attached to trochanters obliquely; femora clavate, wider distally just before apices; tibiae similar in length to femora, slender and covered laterally along apical onethird with a brush of setae on all legs; tibial spurs small,?–?–2 ( Fig. 4B ). Tarsal length 0.7 times tibial length; tarsomere 1 enlarged and emarginate; tarsomere 2 shorter and more strongly emarginate; tarsomere 3 strongly bilobed; tarsomere 4 short and hidden between lobes of tarsomere 3; tarsomere 5 similar in length to lobes of tarsomere 3 and narrow; pretarsal claws not fused, divergent, not appendiculate, with a basal swelling on each claw.

Remarks

Zimmerman (1994) elevated Caridae to family rank, whereas it was previously considered a subfamily of Belidae by Thompson (1992). Albicar gen. nov. is assigned to Caridae based on the elongate antennal scape; antennal insertion laterally and before the middle of the rostrum; large, convex compound eyes; postocular constriction; protuberant pro- and mesocoxae; a pair of small tibial spurs on the metatibiae; and divergent pretarsal claws with a basal swelling. Rhynchitinae (Attelabidae) is a rather similar group if the only visible features are external, and if not for the detailed re-examinations made by Riedel et al. (2012) of Baltocar Kuschel, 1992 [which is a small genus containing Baltocar succinicus ( Voss, 1953) , Baltocar groehni Riedel, 2012 , Baltocar hoffeinsorum Riedel, 2012 , and Baltocar subnudus Riedel, 2012 ], it is quite feasible to confuse the similarities between this genus and Albicar gen. nov. ( Kuschel, 1992). Owing to problems in delimiting many other characters, the longer scape in Albicar gen. nov. should be sufficient to exclude it from Baltocar (and other rhynchitines) and assign it definitively to Caridae . Only five extant genera are included in Caridae , three from Australia (i.e. Car Blackburn, 1897 , Carodes Zimmerman, 1994 , and Crowsonicar Legalov, 2013 ), and two from South America (i.e. Caenominurus Voss, 1965 , and Chilecar Kuschel, 1993 ) ( Kuschel, 1992; Zimmerman, 1994; Oberprieler et al., 2007; Legalov, 2013c). Compiling information on Carodes (in Zimmerman, 1994), Crowsonicar (in Legalov, 2013c), and the new genus Albicar gen. nov. described above, the comparative morphological results are summarized in Appendix 2. Many described fossil Caridae (mostly compression fossils) are excluded from the table owing to the observation that many appear to belong to a separate clade within Caridae ( Legalov, 2009; Gratshev & Legalov, 2011; Davis et al., 2013). The only amber fossil taxon added to this table is Cretocar Gratshev & Zherikhin, 2000 , based on its possible affinity with this family by possessing an elongate antennal scape; short, oblique trochanters; and short tibial spurs ( Gratshev & Zherikhin, 2000).

Cretocar (holotype observed by the authors herein) is similar in age to Albicar gen. nov. and although both fossils are very similar to the extant genus Crowsonicar , several features may distinguish Cretocar and Crowsonicar from Albicar gen. nov. Albicar gen. nov. differs from Cretocar and Crowsonicar by the lateral antennal insertion, the head globose and constricted post-ocularly, elytra emarginate laterally (see Appendix 2), a longer antenna, transverse pronotum, prothorax only slightly narrower than the elytra, and very convex body. It is important to also note a misinterpretation in Cretocar , initially described with a head that is slightly constricted behind the compound eyes ( Gratshev & Zherikhin, 2000). Cretocar has a globose head, similar to the extant genus Car and clearly different from Albicar gen. nov. Although specific characters seem to agree with a placement in Caridae , the general gestalt begs something closer to Nanophyinae (Brentidae) . In reality, however, being able to accurately identify an ancestral nanophyine, or any ancestral or stem-lineage taxon that may possess a different combination of characters from those of the recognized extant clades, would indeed be a formidable task.

Although it is possible that Mesophyletis Poinar, 2006 ( Poinar, 2006, 2008) is also related to the carids included in the data matrix of Appendix 2, we have tentatively decided not to include it based on the atypical set of characters mentioned in the original description, such as geniculate antennae, long trochanters, and the apical tibial spines on the pro- and mesotibiae, alluding more towards a primitive member of Curculionidae . The taxonomic position of Mesophyletis within Caridae is the subject of further investigation.

Albicar gen. nov. closely resembles the Recent Caenominurus but the extant genus is larger (more than 3 mm, without the rostrum), possesses more convex compound eyes, the scape is longer, extending to nearly the middle of the compound eyes, the tibiae are robust, and the elytra bear punctured striae. By contrast, Albicar gen. nov. is 2.3 mm (without the rostrum), the compound eyes are large, but not as protuberant as in Caenominurus , the scape does not extend beyond the anterior margin of the compound eye, the tibiae are slender, and the elytral striae are indiscernible because of the specimen’s preservation.

The new genus is similar in habitus to Abrocar Liu & Ren, 2006, but differs by the more closely inserted, slender antennae with a noncompact club, large and rounded compound eyes, and indiscernible elytral striae. From other fossil genera Albicar gen. nov. differs by the narrower first tarsomere and elongate body.

Figures

Figure 4. Photos and drawings of Albicar contriti gen. et sp. nov. (CES–432, holotype), from Early Cretaceous El Soplao amber (Spain). A, photo and camera lucida drawing of the dorsal habitus; B, photo and camera lucida drawing of the lateral habitus, arrow marks the two spurs at the metatibial apex.