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A new species of the extinct bee genus Ctenoplectrella Cockerell (Megachilinae: Ctenoplectrellini) is described and figured from two females preserved in middle Eocene (Lutetian) Baltic amber. Ctenoplectrella phaeton sp. n. is distinguished from its congeners on the basis of its body proportions, integumental sculpturing, wing venation, and pubescence, and is one of the more distinctive members of the genus. A revised key to the species of Ctenoplectrella is provided.
Megachilinae, Ctenoplectrellini, paleontology, Tertiary, Eocene, taxonomy
The Eocene was the last epoch harboring a truly disparate
bee fauna relative to the composition of forms we are so familiar with
in today’s ecosystems. Following the Eocene-Oligocene transition the bee
fauna began to look relatively modern at least in terms of the general
appearance of the tribes, genera, and subgenera comprising the
diversity in the latest Paleogene and Neogene periods. However, from
the Eocene and earlier epochs we find regularly taxa that harbor unique
combinations of traits that render them challenging to fit amongst their
modern counterparts even at higher taxonomic levels, alongside
otherwise more modern forms (
Herein we describe a recently recognized new species of the Eocene bee genus Ctenoplectrella (
Currently included species in Ctenoplectrella.
Species | References |
---|---|
Baltic Amber (Lutetian) | |
Ctenoplectrella cockerelli Engel, 2001 |
|
Ctenoplectrella gorskii Engel, 2008 |
|
Ctenoplectrella grimaldii Engel, 2001 |
|
Ctenoplectrella phaeton Gonzalez & Engel, sp. n. | Present study |
Ctenoplectrella viridiceps Cockerell, 1909a |
|
Rovno Amber (Bartonian-Priabonian?) | |
Ctenoplectrella zherikhini Engel & Perkovsky, 2006 |
|
While Ctenoplectrella and Glyptapis are definite oddities, we have noted a considerable similarity between Ctenoplectrella and the rare living genus Aspidosmia Brauns [presently in Anthidiini (vide
Morphological terminology follows that of
urn:lsid:zoobank.org:act:0027DEF4-DC4A-46C2-87C4-473120D5BB80
http://species-id.net/wiki/Ctenoplectrella_phaeton
Figs 1–4♀, AMNH Ba-JVe-161, Baltic amber, middle Eocene (Lutetian). Deposited in the Amber Fossil Collection, Division of Invertebrate Zoology (Entomology), American Museum of Natural History, New York.
♀, on curved edge in same amber piece as holotype and with same repository (Figs 1, 4).
Photograph of majority of amber piece (middle Eocene, Baltic amber) indicating relative positions of two individuals of Ctenoplectrella phaeton Gonzalez and Engel, sp. n. (AMNH Ba-JVe-161); holotype is at right, paratype at upper left on curved edge of piece.
This species resembles Ctenoplectrella cockerelli Engel in the forewing with vein 2rs-m strongly and doubly arcuate, the basal vein confluent with cu-a, the first submarginal cell shorter than the second submarginal cell, and the punctate mesepisternum and terga. However, Ctenoplectrella phaeton can be distinguished from Ctenoplectrella cockerelli and remaining species of the genus by its robust body, punctate metepisternum (impunctate in Ctenoplectrella cockerelli), and much shorter and sparser body pubescence.
Female: Total body length 5.77 mm (6.15 mm); forewing length 3.85 mm (3.92 mm). Head slightly wider than long; paraocular carina present; pedicel about as long as combined lengths of first and second flagellomeres; interocellar distance 2.5 times median ocellar diameter, 1.5 times longer than ocellocular distance; ocelloccipital distance about 1.6 times median ocellar diameter. Intertegular distance 1.46 mm. Outer surfaces of pro– and mesotibiae apically with small posterior spine. Prestigma relatively short, slightly more than two times longer than broad (prestigma width measured to its margin); basal vein strongly arcuate, confluent with cu-a; second abscissa of Rs basad 1m-cu by about six times vein width; 2rs-m distad 2m-cu by vein width, 2rs-m doubly arcuate; second submarginal cell slightly longer than first submarginal cell; seven distal hamuli, arranged in a single, evenly-spaced series. Sixth metasomal sternum with broadly rounded apical margin.
Integument in general smooth and shiny between punctures, weakly imbricate laterally on terga. Outer surface of mandible with minute punctures separated by a puncture width or less. Frons with small punctures separated by 1–1.5 times a puncture width, punctures becoming denser towards vertex. Pronotum laterally with minute punctures separated by a puncture width or less. Mesoscutum with small punctures separated by 1–2 times a puncture width (Fig. 2); tegula with minute, scattered punctures; mesoscutellum about as punctate as on mesoscutum. Metanotum impunctate and smooth. Mesepisternum with faint, scattered, larger punctures than on mesoscutum, nearly impunctate anteriorly to omaulus, punctures denser ventrally. Metepisternum more densely punctate than on mesepisternum, punctures separated by a puncture width or less dorsally, punctures sparse ventrally. Propodeum impunctate basally, lateral and posterior surfaces with minute punctures separated by more than two times a puncture width. Metasomal terga with small punctures separated by 1–2 times a puncture width, without distinct depressed marginal zones; sterna with coarser punctures than on terga, punctures smaller and finer on first sternum.
Photomicrographs of Ctenoplectrella phaeton Gonzalez and Engel, sp. n. (AMNH Ba-JVe-161) in middle Eocene Baltic amber. 2 Dorsal aspect of holotype female 3 Ventral aspect of holotype female 4 Dorsal aspect of paratype female.
Color apparently brown, without maculations. Wing membrane hyaline; veins strong and dark brown.
Face with minute, appressed, simple setae not obscuring integument. Mesoscutum and mesoscutellum with scattered, short, simple setae. Mesepisternum with scattered, erect, longer setae (0.5 times median ocellar diameter) than on mesoscutum. Basal area of propodeum without pubescence; lateral and posterior surfaces with minute, sparse setae (integument largely visible among setae). Legs in general with short, scattered, minutely-branched setae (Fig. 3); basitarsi with denser, slightly longer setae than on tibiae; metatibia with scattered, minutely-branched setae (setal length about 1–1.5 times median ocellar diameter). Metasoma with scattered, short (≤ 0.5 times median ocellar diameter), simple, erect to suberect setae on discs; sternal scopa composed of bands of rather sparse, long (2.5–3.0 times median ocellar diameter), erect, simple setae.
Male: Unknown.
The specific epithet is taken from Phaeton and treated as a noun in apposition. In Greek mythology Phaeton died when he tried to drive the chariot of the sun across the sky. Phaeton’s sisters wept and their tears turned to amber.
The supraclypeus, clypeus, and mandibles are obscured by dense Schimmel (whitish froth of microscopic bubbles resembling mold) in the holotype and by a fracture in the amber piece in the paratype. However, the strong apical tooth and distinct outer ridge of the mandible is barely visible in the holotype, thus suggesting a similar mandibular shape as in other species of Ctenoplectrella.
(updated from
1 | Forewing 2rs-m strongly and doubly arcuate, thus second submarginal cell more strongly produced toward wing apex along posterior margin; medioapical margin of clypeus straight (shape of clypeus unknown in Ctenoplectrella phaeton) | 2 |
– | Forewing 2rs-m relatively straight and therefore second submarginal cell not more strongly produced toward wing apex along posterior margin; medioapical margin of clypeus gently convex | Ctenoplectrella viridiceps Cockerell |
2 | Forewing basal vein confluent with cu-a; first submarginal cell shorter than second submarginal cell | 3 |
– | Forewing basal vein distad cu-a; first submarginal cell longer than second submarginal cell | Ctenoplectrella gorskii Engel |
3 | Mesepisternum impunctate laterally; metasomal terga faintly imbricate | 4 |
– | Mesepisternum with coarse, faint punctures laterally; metasomal terga with small, scattered punctures | 5 |
4 | Propodeal setae long, erect, and branched; tarsal setae fuscous; gena tapering in width from widest above to narrower below | Ctenoplectrella zherikhini Engel & Perkovsky |
– | Propodeal setae scattered, short, and simple; tarsal setae white or off-white; gena of relatively equal width along its length | Ctenoplectrella grimaldii Engel |
5 | Metepisternum punctate; body pubescence distinctly short and sparse | Ctenoplectrella phaeton sp. n. |
– | Metepisternum impunctate; body pubescence of moderate length, not distinctly short and sparse | Ctenoplectrella cockerelli Engel |
We are grateful to D.A. Grimaldi for bringing this material to our attention and permitting its study, to I.A. Hinojosa-Díaz for assistance with microphotography, and to two anonymous reviewers for comments on the manuscript. This is a contribution of the Division of Entomology, University of Kansas Natural History Museum.