PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 Number 3513, 9 pp., 8 figures, 3 tables May 17, 2006 A New Alderfly in Baltic Amber (Megaloptera: Sialidae) WILFRIED WICHARD1 AND MICHAEL S. ENGEL2 ABSTRACT A new species of alderfly (Megaloptera: Sialidae) is described and figured from a rare adult specimen preserved in middle Eocene (Lutetian) Baltic amber. Sialis (Protosialis) voigti, new species, is distinguished from the two other species of Protosialis recorded from Baltic amber. The Megaloptera documented from Baltic amber are briefly overviewed and the geological history of Sialidae summarized. INTRODUCTION brates. The final-instar larva emerges from the water and pupates in a chamber dug into soft The Megaloptera (alderflies, dobsonflies, soil. The adults are relatively short-lived, some and fishflies) are relatively primitive members living merely a week, and spend almost all of of the holometabolan superorder Neuro- their time in vegetation near water. pterida, notable for the plesiomorphic re- Since Megaloptera are essentially aquatic tention of a broad anal region in the hind insects, at least in their immature stages, their wing. The order consists of about 275 species occurrence in Baltic amber is not common. distributed throughout the world and segre- Indeed, only 15–20 inclusions of adult gated into two modern families—the large Megaloptera seem to be known. Remark- and robust Corydalidae (dobsonflies, fish- ably, two mature larvae are also known as flies), and the more diminutive Sialidae amber inclusions, both of the family (alderflies). Larvae of both families are aquat- Sialidae—the first recorded by Weidner ic and generalist predators of small inverte- (1958; Weitschat and Wichard, 2002), the 1 Institut fu¨r Biologie und ihre Didaktik, Universita¨t zu Ko¨ln, Gronewaldstraße 2, D-50931 Ko¨ln, Deutschland ([email protected]). 2 Division of Invertebrate Zoology, American Museum of Natural History; Division of Entomology (Paleoentomology), Natural History Museum, and Department of Ecology and Evolutionary Biology, 1345 Jayhawk Boulevard, Dyche Hall, University of Kansas, Lawrence, Kansas 66045-7163 ([email protected]). Copyright E American Museum of Natural History 2006 ISSN 0003-0082 2 AMERICAN MUSEUM NOVITATES NO. 3513 SYSTEMATIC PALEONTOLOGY Genus Sialis Latreille Sialis Latreille, 1802: 290. Type species: Heme- robius lutarius Linnaeus, 1758, by monotypy. Protosialis van der Weele, 1909: 263. Type species: Semblis americanus Rambur, 1842, by original designation. [recognized as a subgenus] Ilyobius Enderlein, 1910: 381. Type species: Ilyobius flavicollis Enderlein, 1910, by orig- Fig. 1. Photomicrograph of a mature alderfly inal designation. [5 Protosialis] larva in middle Eocene Baltic amber (private Nipponosialis Kuwayama, 1962: 329. Type collection of Mr. Ju¨rgen Velten, Idstein). species: Sialis jezoensis Okamoto, 1910, by original designation. [5 Sialis s.str.] second nearly a half a century later by Protosiails Penny, 1977: 9. Lapsus calami pro Wichard (2005: fig. 1). These larvae were Protosialis. almost assuredly entombed shortly after leav- DIAGNOSIS: Adult with head prognathous ing the water and while attempting to find and relatively flattened; compound eyes large, a suitable location for a pupal chamber. In positioned laterally; ocelli absent; antennae total the Baltic amber fauna contains seven filiform; mandibles strong, multidentate. species of Megaloptera, summarized in ta- Pronotum broad (width up to twice length), ble 1. rectangular or trapezoid; meso- and meta- Herein we provide the description of a new thorax of equivalent proportions and design. species of alderfly recently recognized in Baltic Legs moderately long and stout; tarsi pentam- amber. The new species belongs to the modern erous, fourth tarsomere bilobed (and heart- genus Sialis and the subgenus Protosialis in shaped), with fifth tarsomere inserted near particular, and is known from two adult base. Wings well developed, with complete females. Morphological terminology and ve- venation typical of the order; fore- and hind national nomenclature follow that employed wings with Sc fusing with R1 before wing elsewhere for Megaloptera (e.g., Wichard, apex, R3 forked in Sialis s.str., simple in 1997, 2002). The age and origin of Baltic Protosialis,M1+2 simple; forewing with M3+4 amber has been reviewed by Weitschat and forked (New and Theischinger, 1993). Males Wichard (2002) and Grimaldi and Engel with nine, females with seven fully exposed (2005). abdominal segments. COMMENTS: The foundation for the classi- fication and determination of species of Sialidae are the works of Lestage (1927) TABLE 1 and Weele (1909, 1910). Weele (1909, 1910) Baltic Amber Megaloptera established Protosialis as a separate genus. Later, Ross (1937) considered Protosialis Family CORYDALIDAE Leach 1815 a synonym of Sialis, and Whiting (1994) {Chauliodes prisca Pictet-Baraban In Pictet-Baraban and Hagen 1856 considered the group to be a basal subgenus. {Chauliodes carsteni Wichard 2003 Today some authors prefer to retain Family {CORYDASIALIDAE Wichard et al. 2005 Protosialis as generically distinct, but we {Corydasialis inexpectatus Wichard et al. 2005 consider it as a subgenus pending a compre- Family SIALIDAE Leach 1815 hensive cladistic analysis of species in Sialidae. {Sialis groehni Wichard 1997 Unlike Sialis s.str., Protosialis has R3 simple {Sialis (Protosialis) baltica Wichard 1997 in both the fore- and hind wings while this {Sialis (Protosialis) herrlingi Wichard 2002 vein is forked in the former group (New and {Sialis (Protosialis) voigti Wichard and Engel n.sp. Theischinger, 1993). 2006 WICHARD AND ENGEL: BALTIC AMBER ALDERFLY 3 TABLE 2 challenging to discern in the left hind wing). Comparison of Baltic Amber Protosialis Female terminalic sclerites as depicted in figure 6; sternite VIII with two, well-differen- baltica herrlingi voigti tiated, lateral calli. HOLOTYPE: Adult female in middle Eocene R2 in both wings simple simple forked M3+4 in hind wing forked simple simple Baltic amber (figs. 2, 3); accession number KU-NHM-ENT, B-003; located in the Fossil Insect Collection, Division of Entomology, University of Kansas Natural Sialis (Protosialis) voigti, new species History Museum, Lawrence, Kansas. Figures 2–8 PRESERVATION: The holotype is on one side of a large, oval piece of clear, yellow amber of DIAGNOSIS: The new species shows the maximally 39 mm length and 20 mm width, diagnostic combination of features typical of with a mass of 3.3 g. In the immediate vicinity the subgenus Protosialis; i.e., R3 and M1+2 are of the alderfly is a partial caddisfly (only the both unforked in the fore- and hind wings and front half of the body preserved, the distal half M3+4 is forked in the forewing (New and of the body and the distal third of the wings Theischinger, 1993). The new species can most are cut off) along the amber’s edge. The readily be distinguished from the other maxillary palps, antennae, and legs permit Protosialis species in Baltic amber by the identification of the caddisfly as a species of combination of R2 forked in both fore- and Leptoceridae (Trichoptera). The remaining hind wings and by M3+4 unforked in the hind and larger portion of the amber contains fine wing (table 2). In addition, R4 and R5 in both detritus and numerous stellate trichomes, the fore- and hind wings are unforked. characteristic of Baltic amber. DESCRIPTION: Female. Total body length The alderfly is in remarkably good condi- approximately 11.5 mm. Integument imbri- tion and, aside from being rather complete, is cate and dark brown where evident; wing also well positioned in the amber, permitting veins dark brown, membrane hyaline. Head detailed examination. The specimen has some about as long as wide, with large compound Schimmel (a froth of microscopic bubbles) eyes positioned laterally on anterior half of obscuring the integument in some areas, but head. Mandibles stout; maxillary palpi 5- none of it prevents identification. The right segmented; labial palpi 3-segmented; other forewing is rather extensively damaged along mouthpart structures not discernable. Left its leading edge while the left forewing is antenna with 28 antennomeres (i.e., including complete, only slightly obscured near the apex scape and pedicel), right antenna partial; of its posterior margin by the left hind wing flagellomeres of roughly equal size, each being partly folded forward (figs. 4, 5). Both slightly longer than wide. Ocelli absent. Tarsi hind wings can be seen in ventral aspect and, of typical pentamerous construction, with despite a few minor folds and some obscuring fourth tarsomere bilobed and heart-shaped by the abdomen, the venation can be easily (distinguishing feature of Sialidae, along with discerned (figs. 4, 5). The legs are complete the absence of ocelli). Forewing approximate- and preserved folded beneath the body. The ly 14 mm in length; costal field weakly arched, right antenna is incomplete, but the left giving wing a slender form; seven c-sc cross- antenna is well preserved. The mouthparts veins present before termination of Sc; R1 are not easily viewed, except for the palpo- running parallel with Sc (with narrow sub- meres of the labium and maxilla, which can be costal cell between them) before veins merge distinguished. The venter of the abdomen is near wing midpoint; R2 forked near wing easily examined, and the female genital apex; R3,R4, and R5 simple at wing apex; sclerites can be sufficiently discerned (fig. 6). M1+2 simple; M3+4 forked near wing apex. ADDITIONAL MATERIAL: An adult female in Hind wing with R2 forked near wing apex; R3, middle Eocene Baltic amber (figs. 7, 8); R4,R5,M1+2, and M3+4 simple (the last vein is specimen in the collection of Ju¨rgen Velten, easily seen in the right hind wing but Idstein, Germany. 4 AMERICAN MUSEUM NOVITATES NO. 3513 Figs. 2–3. Photomicrographs of the holotype female of Sialis (Protosialis) voigti, n.sp. 2. Dorsal aspect. 3. Ventral aspect. 2006 WICHARD AND ENGEL: BALTIC AMBER ALDERFLY 5 Figs. 4–5.