Research Article |
Corresponding author: Zhenhua Liu ( liuzhh22@mail2.sysu.edu.com ) Corresponding author: Hong Pang ( lsshpang@mail.sysu.edu.cn ) Academic editor: Pavel Stoev
© 2020 Xueyong Du, Adam Slipinski, Zhenhua Liu, Hong Pang.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Du X, Slipinski A, Liu Z, Pang H (2020) Description of a new species of Eucinetidae (Coleoptera, Scirtoidea) from Cretaceous Burmese amber. ZooKeys 982: 1-9. https://doi.org/10.3897/zookeys.982.39335
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Eucinetus parvus sp. nov. is described from late Cretaceous Burmese amber, representing the second record of Eucinetidae from the Burmese amber and the first species of the family with simple, not piercing, mouthparts. A comparison between Mesocinetidae and Eucinetidae is provided.
Eucinetus, generic diagnosis, relationship
The family Eucinetidae Lacordaire, 1857 is a relatively small group in the polyphagan Coleoptera, consisting of 10 extant genera and fewer than 60 species distributed worldwide (
The fossil record of Eucinetidae is sparse. The fossil genus Mesocinetus Ponomarenko, 1986, which was described from the early Cretaceous of the Gurban-Eren Formation in western Mongolia (
Here, a new fossil species of the extant genus Eucinetus (Eucinetidae) with simple mouthparts from Burmese amber is presented. This new species demonstrates the ancient origin of this lineage of beetles.
The specimen included in this study is embedded in Burmese amber from the Hukawng Valley of northern Myanmar (
For preparation, the amber material was polished with emery papers of various grits and polished with polishing powder. Images were taken using a Nikon DS-Ri2 camera mounted on a Nikon SMZ25 microscope; layers were captured and aligned using NIS-Elements software and processed in Photoshop CC. The line drawings were prepared in Adobe Illustrator CC and figures were compiled in Photoshop CC. The length of the beetle specimen was measured from the anterior margin of head to the apex of elytra; the width is the maximum width of the elytra. Morphological terminology of Eucinetidae follow
Family Eucinetidae Lacordaire, 1857
Scaphidium haemorrhoidalis Germer, 1818.
Eucinetus can be separated from Bisaya, Eucilodes, Jentozkus, Proeuzkus, Tohlezkus, and Cretohlezkus by having the simple labium. Among the other genera, it differs from Eucinetella and Euscaphurus in the filiform antenna and broad labrum, and from Noteucinetus in the slender body shape and transverse rows of striae on elytra. Eucinetus is most similar to Nycteus except that antennomere 3 in Nycteus is distinctly shorter than the adjacent segments, which is almost the same length as antennomere 4 in Eucinetus.
Latin, parvus, meaning small, which refers to the small body size of the new species.
SYS-ENAM0011, female.
Hukawng Valley, Kachin State, northern Myanmar; lowermost Cenomanian, Upper Cretaceous.
The new species can be distinguished from all the extant species of Eucinetus by the combination of the following characters: relatively small and narrower body; slenderer mesepimeron and matanepisternum; relatively short antenna with the scape shorter than pedicel. It can also be easily separated from Eucinetus nikolaevae by much smaller body (1.9 mm long compared to 2.8 mm in E. nikolaevae), slender body-shape, and sub-rectangular labrum.
Length about 1.9 mm, width 0.7 mm. Body elongate-fusiform (Fig.
Head relatively small, subtriangular; posterior margin nearly truncate. Eyes moderately large, protruding, and finely facetted. Temple behind eyes moderately long; posterior angles orthogonal. Antennae closely inserted in front of eyes in antennal fossae. Antenna (Fig.
Pronotum transverse, widest posteriorly; anterior margin broadly rounded, lateral margins gradually widened posteriorly, and posterior margins sinuate; disc with distinct microsculpture, uniformly covered by dense, short setae. Prosternum highly reduced with very narrow area in front of procoxae; prosternal process narrow. Notosternal suture present. Procoxae strongly transverse and projecting, nearly contiguous, and protrochantins exposed; procoxal cavities externally widely opened.
Elytra elongate, about 2.3 times as long as wide, lateral margins gradually narrowed posteriorly, apex sharp; dorsal surface with dense, distinct, transverse microsculpture and covered by dense, uniform setae; epipleuron not extending to apex and relatively narrow at base. Mesoventrite short, with deep, longitudinal, middle depression fitting fore femur. Mesanepisternum large and subrectangular; mesepimeron large and subtrapezoid. Mesocoxal cavities (Figs
The placement of the new species in Eucinetidae is based on the combination of hypognathous head, fusiform body shape, 5-5-5 tarsal formula, fringes of spines on apex of tibiae and tarsomeres, and huge metacoxal plates. Unlike Cretohlezkus, which was described from Burmese amber (
Eucinetidae is closely related to the fossil family Mesocinetidae, which is distinguished mostly by the large metacoxal plates, very short metaventrite, and widened metanepisternum (
This project was funded by the following grants awarded to HP: Key project of Science-technology Basic Condition Platform from the Ministry of Science and Technology of the People’s Republic of China (no. 2005DKA21402); the Specimen Platform of China, teaching specimens sub-platform, http://mnh.scu.edu.cn/; and to AS: Open Project of the State Key Laboratory of Biocontrol (grant no. 2018-04). We also wish to thank P. Jałoszynski for providing us with several references.