N. Jb. Geol. Paläont. Abh. 2008, vol. 247/3, p. 353–381, Stuttgart, March 2008, published online 2008 The enigmatic Mesozoic insect taxon Chresmodidae (Polyneoptera): New palaeobiological and phylogenetic data, with the description of a new species from the Lower Cretaceous of Brazil Xavier Delclòs, Barcelona, André Nel, Paris, Dany Azar, Fanar-Matn, Günter Bechly, Stuttgart, Jason A. Dunlop, Berlin, Michael S. Engel, Lawrence, and Sam W. Heads, Portsmouth With 10 figures DELCLÒS, X., NEL, A., AZAR, D., BECHLY, G., DUNLOP, J. A., ENGEL,M.S.&HEADS, S. W. (2008): The enigmatic Mesozoic insect taxon Chresmodidae (Polyneoptera): New palaeobiological and phylogenetic data, with the description of a new species from the Lower Cretaceous of Brazil. – N. Jb. Geol. Paläont. Abh., 247: 353–381; Stuttgart. Abstract: The morphology of the enigmatic, Mesozoic, aquatic insect family Chresmodidae is redescribed and its phylogenetic affinities among the polyneopterous orders discussed. Study of the complete venation of both fore- and hind wings observed in some specimens from the Spanish Barremian, permit us to postulate the hypothesis that the family belongs to the Archaeorthoptera, thus to the orthopteroid lineage rather than to crown-group Phasmatodea or to the more inclusive group Holophasmatodea (sensu GRIMALDI &ENGEL, 2005). New specimens from Spain, Lebanon, Brazil, and Germany permit a new re-description of some chresmodid body structures with concomitant implications for the phylogenetic position of the family. Chresmoda neotropica n. sp. is described from the Aptian-Albian of the Crato Formation (northeast Brazil). The functional morphology eschweizerbartxxx proposed for some of their specialized structures suggest a new hypothesis of Chresmoda palaeo- biology, and related to this some implications for the localized palaeoenvironment as well as global palaeoclimate. The problematic Sternarthron spp. from the Upper Jurassic of Solnhofen were described as probable palpigrades (Arachnida: Palpigradi), based on type material originally thought to be fossil insects. The affinities of Sternarthron HAASE, 1890 have been questioned. Our restudy of HAASE’s types clearly confirmed earlier assumptions that these fossils represent nymphal specimens of chresmodids. Consequently, Sternarthron has to be considered as an invalid junior synonym of the fossil insect genera Propygolampis WEYENBERGH, 1874 and Chresmoda GERMAR, 1839. Key words: Insecta, Polyneoptera, Archaeorthoptera, Sternarthronidae, Chresmodidae, Palpigradi, Functional Morphology, Phylogeny, Paleoecology, Mesozoic, Crato Formation, Solnhofen Litho- graphic Limestones. 1. Introduction and historical context tarsi with more than 40 tarsomeres (Fig.7.2), a feature which is unique within Insecta (NEL et al. 2004). The Chresmodids are large fossil insects with a water- forelegs are usually directed anteriorly, while the strider-like habitus. They have short and thick middle and hind legs are directed latero – posteriorly. antennae and prognathous chewing mouthparts with They have two pairs of membranous wings with a strong mandibles, and large compound eyes. The legs slender forewing with long and parallel longitudinal are extremely prolonged with very long femora, veins and a broad anal fan in the hind wings, typical of shorter tibiae, and long, multi-segmented, flagellate polyneopterous insects (Figs.6.3, 8). There are long, DOI: 10.1127/0077-7749/2008/0247-0353 0077-7749/08/0247-0353 $ 7.25 © 2008 E. Schweizerbart’sche Verlagsbuchhandlung, D-70176 Stuttgart 354 X. Delclòs et al. monomerous, lancelolate cerci at the end of the ab- He considered the types of both P. bronni and C. domen (similar to Phasmatodea), and females have a obscura to be unusable, since the original fossils had prominent orthopteroid ovipositor. Males seem to be been painted in (a ‘bemalter Artefact’), but gave no apterous. The nymphs are similar to the adults except justification for rejecting Propygolampis as a valid for a much smaller size, a distinctly shorter abdomen, name and substituting his own name, Halometra;now and the absence of wings. Consequently the deve- regarded as a junior synonym of Propygolampis (e.g. lopment of chresmodids was heterometabolous as CARPENTER 1992). OPPENHEIM, like GERMAR, thought in orthopterans and other polyneopterous insects. H. gigantea was a semiaquatic hemipteran, referring Chresmodids probably lived on the surface of lakes the genus to the family Hydrometridae. In addition and lagoons (contra BAUDOIN 1980 who did not know to this, he described a further Solnhofen species, the true structure of chresmodid legs), and fed on Halometra ? minor OPPENHEIM (1888) based on three insects and other small animals at the water surface, smaller fossils in the Bayerische Staatssammlung für just like the unrelated, but superficially similar, Paläontologie und Geologie, Munich. Although modern Gerridae. Because of their significant larger OPPENHEIM (1888) was uncertain about the generic size and weight it cannot be excluded that chresmo- affinities of H.? minor, he specifically noted that the dids might have needed floating water plants near overall shape and number of legs (i. e., six) meant the shore to support their heavy bodies on the water that they could not be crustacean larvae or arachnids. surface. The group is exclusively Mesozoic and may CARPENTER (1992) propagated the younger synonym have suffered extinction during the Late Cretaceous Propypolampis WEYENBERGH, 1874 as the valid name greenhouse climate. for the fossils previously known as Chresmoda Since GERMAR (1839) named Chresmoda obscura GERMAR, 1839, and mentions a paper by himself for an insect found in the Upper Jurassic of Soln- (listed as “in press” for 1992) that allegedly revealed hofen-Eichstätt, the taxonomic placement of this the holotype of Chresmoda to be a locust and was only enigmatic species has been dramatically reinterpreted later confused with the “fossil water striders”. There- several times. GERMAR (1839) originally established fore, CARPENTER (1992: 181) classified Chresmoda the species for a “flattened-like shaped insect, with a within Orthoptera-Caelifera as a “little-known genus pronotum and with long hind legs”, and placed it probably related to Acrididae”, while he considered among the mantises (Mantodea). In the same paper he Propygolampis to be related to Phasmatodea. How- established also the species Pygolampis giganteaeschweizerbartxxx , ever, the cited paper of CARPENTER that was sup- which was a larger insect, similar to C. obscura,but posedly “in press” in 1992 in the journal Psyche was with forelegs shorter than the mid- and hind legs. never published (FURTH 1994) and the manuscript has GERMAR believed P. gigantea was a hemipteran to be considered as lost because it is neither archived similar to the living water-strider Gerris. This paper with the intended publisher nor could it be found introduced an immediate nomenclatural problem since among CARPENTER’s archives in his laboratory at the GERMAR actually ascribed both species names to his MCZ (GB and MSE, pers. obs.). compatriot, MÜNSTER, although MÜNSTER was not an HANDLIRSCH (1906-1908) proposed that Pygo- author on this paper and the work is clearly that of lampis gigantea was a junior synonym of Chresmoda GERMAR. Subsequent authors (e.g. CARPENTER 1992) obscura, and established the new family Chresmo- have correctly treated GERMAR as the author of these didae and providing a discussion about its inclusion taxa. WEYENBERGH (1869: 27) listed “Pygolampis in Phasmatodea or Orthoptera. Subsequently, HAND- gigantea GERM.” and mentioned three beautiful fossils LIRSCH (1925, 1926-1930) considered chresmodids as of this species from the Teyler Museum in Haarlem, of aquatic phasmatodeans. Unfortunately, the holotype which he figured one (pl. 2, fig. 21) with the catalogue of C. obscura is missing, whereas the holotype of P. number 6395. Subsequently, a similar fossil hemi- gigantea is housed in the Munich Museum (Fig. 2.1). pteran genus Propygolampis WEYENBERGH, 1874 was HANDLIRSCH (1906-1908) placed Gryllidium oweni created for a new Solnhofen species, Propygolampis WESTWOOD, 1854 into Chresmoda. The latter is an bronni WEYENBERGH, 1874. Meanwhile, ASSMANN isolated forewing with longitudinal veins and with (1877) synonymised P. gigantea with C. obscura, re- dense crossveins and basal archaedyction, the holo- garding them as orthopterans. OPPENHEIM (1888) later type of which is now lost (SWH pers. obs.). synonymised P. gigantea, C. obscura, and P. bronni MARTYNOV (1928) placed the suborder Chresmo- under the name Halometra gigantea (GERMAR, 1839). dodea into the Phasmatodea, including four families The enigmatic Mesozoic insect taxon Chresmodidae from the Lower Cretaceous of Brazil 355 related by their wing venation: Chresmodidae (Trias- Orthopterida (i.e., secondarily autapomorphic for sic-Cretaceous), Aeroplanidae (Triassic), Necrophas- Phasmatodea). Some authors place them close to the matidae, and Aerophasmidae (both Jurassic). ESAKI Embiodea, or even with modern Grylloblattodea and (1949) established the species Chresmoda orientalis Mantophasmatodea (see discussion below). More for an insect with short body (24 mm), but with long critical work on the phylogenetic relationships of legs and antennae (11 mm), from a specimen found Phasmatodea and putative relatives is required. in the Upper Jurassic of Ta-hsing-fang-tzu, Jehol in Numerous discoveries in the Upper Jurassic of China (this specimen is also missing today). Germany and Lower