FNZ 45 - Nemonychidae, Belidae, Brentidae (Insecta: Coleoptera: Curculionoidea) - Fossils
Kuschel, G 2003. Nemonychidae, Belidae, Brentidae (Insecta: Coleoptera: Curculionoidea). Fauna of New Zealand 45, 100 pages.
(
ISSN 0111-5383 (print),
;
no.
45.
ISBN 0-478-09348-9 (print),
).
Published 28 Apr 2003
ZooBank: http://zoobank.org/References/9143DAB5-942F-4E3B-8E68-D47BB28498D5
FOSSIL EVIDENCE
No fossils of weevils of Tertiary, or earlier ages, have been described from New Zealand, but many are known from other parts of the globe. Russian entomologists have excelled in describing a rich assortment of fossil Coleoptera from Triassic, Jurassic, and Cretaceous sediments of the Russian Federation of countries, notably from the particularly rich deposits at Karatau in Kazakhstan, and from areas of other continents. A brief account of proposed fossil weevil families is given below, with comments on their validity and relevance to the extant fauna.
Four families have been proposed in the last 25 years:
- Eobelidae by Arnoldi (1977), based on 30 species in 15 genera and four subfamilies, from the Upper (Late) Jurassic;
- Eccoptarthridae by Arnoldi (1977), on one genus and species from the same deposits, originally in a tribe of Eobelidae, whose status was twice changed, firstly by Zherikhin & Gratshev (1995), by citing it as a subfamily of Nemonychidae, then (1997) by raising it to independent family;
- Ulyanidae by Zherikhin (1993) on one genus and species from the Middle Cretaceous of the West Okhot Region;
- Obrieniidae Zherikhin & Gratshev (1994), on seven species in five genera and two subfamilies from the Upper Triassic and Upper Jurassic.
Obrieniidae. Obrieniidae was described as the earliest family of Curculionoidea, but there appears to be no or little ground for a placement in the superfamily of weevils. The features regarded as stable and basic for extant weevil groups, as invariably found in Nemonychidae, Anthribidae, Belidae, and Attelabidae, ought to be expected to show up in Obrieniidae, but this is not the case. The only character that seemingly determined a placement of Obrieniidae in Curculionoidea was the presence of a head extended forward into a kind of rostrum. An extended head alone, however, does not define a curculionoid because it is also known in a number of other beetle groups. The 9 main features against a placement of Obrieniidae in Curculionoidea are:
- middle coxae in direct contact with mesepimera and metepisterna, a character not found in any curculionoid;
- absence of a scutellar striole, now the case only in Caridae, Brentidae, and Curculionidae;
- width of the sutural interstria the same throughout, instead of distinctly broader in the basal area;
- a sternopleural suture touching fore coxae anterolaterally, instead of fully laterally on the outer side of the coxae;
- absence of distinct tibial combs;
- first three antennal segments equally robust instead of two at most;
- a compact antennal club instead of a loosely articulated club;
- elytral striae well marked throughout, instead of weak or effaced posteriorly;
- interstriae 2 and 3 joining 9 and 8, instead of joining 10 and 9.
Every one of these nine characters would almost certainly exclude Obrieniidae from Curculionoidea, in particular the contiguity of the middle coxae and the pleurites, and the simultaneous absence of a scutellar striole and a basally broadened sutural interstria. On the other hand, character (1), listed above, seems to be in agreement with what is seen in extant Archostemata.
Eobelidae. A merger of Eobelidae with Nemonychidae was suggested by Kuschel (1983) and accepted by Zherikhin (1986). Some Eobelidae were subsequently transferred by Zherikhin & Gratshev (1995) to Belidae, though with some reservation, in a study of hind wings of Curculionoidea. These authors had a fragment of a wing, attributed to a Probelus species, which was showing little more than the stigmatical area. The radial cell and window of the fossil wing is triangular in shape, similar to those observed in some extant Belidae. The shape of the cell and window, however, varies a good deal in Belidae as well as in Nemonychidae. It can be a narrow, elongate triangle, as in the tribe Belini and the megalopodid genus Palophagus, or a broader triangle, as in Probelus and the nemonychid genus Mecomacer. There can also be a broad cell and window of a tetragonal or pentagonal shape, as in the belid subtribe Agnesiotidina and in Nemonyx. Fossil taxa seldom provide a good set of reliable characters and thus become prone to being moved about by different scientists and sometimes by the same scientist at different times. I contend that the features of the rostrum, mandibles, antennae, legs, and elytral striae suggest a much safer position of Eobelidae in Nemonychidae than in Belidae, because the shape of the radial cell and window alone do not define either family.
Ulyanidae. It is admittedly difficult to place the only known fossil in an extant family. It is also difficult to accept that a beetle family has actually become extinct. The abdomen is not that of any brentid or attelabid. The subapical antennae are not those of belids and carids. The elytral sculpture and presence of scales in the fossil rule out Nemonychidae but not Anthribidae. Should a careful re-examination of the fossil bring no changes to the interpretation of the imprints, other fossils may be required to clarify the systematic position of Ulyanidae.
Eccoptarthridae. It was an audacious step by the Russian paleontologists Zherikhin and Gratshev to put together in one family the extant Caridae and the fossil Eccoptarthridae. The identity of these taxa, of such diverse geological ages, was based solely on the presence of one character of doubtful value, the enlargement of the first tarsal segment. Enlarged tarsi are found in some or all species of the nemonychid Mecomacer Kuschel and the belid genera Isocanthodes Zimmerman, Rhinotia Hope, and Stenobelus Zimmerman. In the absence of other features in the fossil(s), there can be no justification in replacing, because of priority, the name of an extant group offering a full set of adult and larval attributes with one that happens to also have enlarged basal tarsal segments. Apart from a relatively broad first tarsal segment, Caridae have in profile a dorsally pronounced convexity, a curved rostrum, distinctly postmed-ian antennae, an elongate antennal scape, and a prothorax that lacks a carinated lateral margin. All these external attributes of extant Caridae are missing from Eccoptarthrus Arnoldi (1977) and Gobicar Gratshev & Zherikhin (1999). These genera have more features in common with the fossil nemonychid Eobelinae than with present-day Caridae.