Research Article |
Corresponding author: Michael S. Engel ( msengel@ku.edu ) Academic editor: Michael Ohl
© 2017 Michael S. Engel, Jennifer C. Thomas, Abdulaziz S. Alqarni.
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:
Engel MS, Thomas JC, Alqarni AS (2017) A new genus of protorhyssaline wasps in Raritan amber (Hymenoptera, Braconidae). ZooKeys 711: 103-111. https://doi.org/10.3897/zookeys.711.20709
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A second species of protorhyssaline wasps (Braconidae) is described and figured from inclusions in Upper Cretaceous (Turonian) amber of the Raritan Formation in New Jersey, USA. Rhetinorhyssalites emersoni, gen. n., sp. n., is distinguished from other protorhyssalines, particularly the contemporaneous Protorhyssalus goldmani.
Apocrita , Euhymenoptera , Ichneumonoidea , parasitoid, Turonian, taxonomy
The parasitoid wasp subfamily Protorhyssalinae includes a variety of generally plesiomorphic cyclostome braconids known only from Cretaceous deposits. The subfamily was initially described based on a species from the Upper Cretaceous (Turonian) amber of New Jersey (
Here we describe a second species of protorhyssaline wasps (Fig.
Two individuals were identified in slightly turbid amber pieces from the Upper Cretaceous Raritan Formation of New Jersey. The amber has been dated palynologically to the Turonian, at approximately 90 Ma, and the localities mapped by
The descriptions are formatted like those recently presented for related Cretaceous braconids (e.g.,
Archaeorhyssalus Engel in Engel & Wang (2016), Diorhyssalus
Rhetinorhyssalites emersoni sp. n.
Head cyclostome, with hypoclypeal depression deep; antenna with 20–24 flagellomeres (18–20 in Protorhyssalus Basibuyuk et al.); flagellum with scattered multiporous plate sensilla; occipital carina present and complete, albeit particularly weak dorsally; compound eyes not emarginate, without evident setae. Pronotal collar short, with subpronope scarcely indicated; notauli deeply impressed, percurrent; mesoscutal lateral areas sculptured as on remainder of mesoscutum; mesoscutellum not raised relative to mesoscutum (distinctly raised in Protorhyssalus); epicnemial carina absent (present in Protorhyssalus: “prepectal carina” sensu
The generic name is a combination of Rhetinorhyssalus Engel, a genus with somewhat similar venation, and the suffix –ites (Greek, “having the nature of”). The gender of the name is feminine.
♂, AMNH NJ-892A; deposited in the Division of Invertebrate Zoology, American Museum of Natural History, New York.
♂, AMNH NJ-692; same locality and repository as the holotype.
Upper Cretaceous (Turonian) amber, New Jersey, Middlesex County, Sayreville, white oaks pit. The locality has been discussed and the Raritan amber deposits mapped by
♂: Total length 2.54 mm as preserved (2.53 mm); forewing length 1.98 mm (1.90 mm), hind wing length 1.66 mm (1.60 mm); integument, where evident, dark brown, lighter on appendages; wing veins dark brown to brown, membranes hyaline and clear.
Head apparently about as long as wide (direct frontal view not possible in either holotype or paratype), with small punctures separated by about 2 or more times a puncture width, integument between smooth, with scattered, suberect, minute setae, setae more numerous on lower face; face below antennal toruli somewhat flat; clypeus slightly protruding, rounded, short; hypoclypeal depression deep and wide; mandible short (mandibles closed in both specimens); labial palpus short, apparently with three palpomeres; maxillary palpus elongate, apparently slightly longer than head, with six palpomeres, palpomeres IV–VI elongate, thinner than preceding palpomeres, palpomere III thickened and dorsally hunched, with abundant distinctive setae dorsally; compound eye large and glabrous, length 0.36 mm, broader than gena, inner margin not emarginate; ocelli positioned close together on top of vertex; occipital carina complete, weak dorsally; antenna slightly shorter than body length; scape squat, only slightly longer than wide, length 0.11 mm, width 0.09 mm, truncate apically; pedicel about as long as wide, slightly narrower than scape, length 0.07 mm, width 0.06 mm; flagellum with 20 flagellomeres (24 flagellomeres); basal flagellomeres elongate, approximately 3–4 times as long as wide, flagellomere I length 0.16 mm, width 0.04 mm; flagellomere II length 0.14 mm, width 0.04 mm; flagellomere III length 0.13 mm, width 0.04 mm; remaining flagellomeres progressively shorter, apical flagellomeres about 1.25–2.0 times as long as wide; multiporous plate sensilla sparse.
Mesosoma length 0.98 mm (0.98 mm); pronotal surface smooth; mesoscutum with minute, setigerous punctures separated by a puncture width or less, integument between punctures smooth; notauli deeply impressed, crenulate, percurrent; lateral sectors of mesoscutum (outside of notauli) distinctly raised, convex, with sculpturing as on remainder of mesoscutum; mesoscutellar sulcus deeply impressed; mesoscutellum not raised, on same level with mesoscutum; mesopleuron largely smooth and impunctate, with borders areolate; sternaulus absent; metapleuron areolate; propodeum coarsely and deeply areolate. Legs slender, with numerous minute setae; tibial spurs short, protibial calcar slightly curved, without comb; metafemur tubular except with weak subapical concavity on inner ventral surface; metatibia length 1.26 mm (1.23 mm); basitarsi longest tarsomeres, but shorter than combined length of remaining tarsomeres, slightly longer than fifth tarsomeres; pretarsal claws short, simple; arolium small. Forewing (Fig.
Metasoma length 1.21 mm (1.20 mm), with terga II and III fused and with distinct suture line; integument generally smooth an impunctate, with scattered, short, appressed setae; first metasomal tergum with dorsal carinae strong, extending to posterior tergal margin, dorsopes deeply impressed and areolate; lateral carinae strong, with lateropes deeply impressed; tergum I about as long as wide, remaining terga wider than long.
♀: Latet.
The specific epithet honors the late William K. Emerson (1925–2016), a leading malacologist with the American Museum of Natural History (
As the name implies, there is some similarity in the wing venation between Rhetinorhyssalites emersoni and the slightly older Rhetinorhyssalus morticinus Engel from Cenomanian amber of Myanmar (
Unfortunately, protorhyssalines remain a great rarity and it is impossible at present to elaborate more fully on these early parasitoids, particularly in regards to their biology. Putatively primitive braconids such as rhyssalines, are ectoparasitoids of larval Coleoptera and Lepidoptera (
The Cretaceous diversity of Braconidae remains scarcely known, although a significant expansion in our knowledge has been made during the last 20 years. Although the family is vast and cosmopolitan today, with about 20,000 described species, its fossil record is scant despite extending well into the Mesozoic. The discovery of Rhetinorhyssalus emersoni in Turonian Raritan amber expands not only our general understanding of the faunal composition of Hymenoptera from the Raritan Formation of eastern North America, but builds upon our meager knowledge of Braconidae from the Cretaceous. Although we still look ‘through a glass darkly’, the continued discovery and description of further species such as R. emersoni remains our only means of clearing our view into the distant history of the braconids and other significant diversifications.
The authors extend their appreciation to the International Scientific Partnership Program (ISPP) at King Saud University for funding this research through ISPP #0083. The manuscript received important and helpful reviews from Daniel J. Bennett and an anonymous evaluator, to whom we are most grateful. This is a contribution of the Division of Entomology, University of Kansas Natural History Museum.