Venational Homologies and Nomenclature in Chrysopidae, with Comments on the Myrmeleontoidea (Insecta: Neuroptera)

Pure and Applied Research in Neuropterology. Proceedings of the Fifth International Symposium on Neuropterology. Cairo, Egypt, 1994. Canard, M., Aspock, H. & Mansell, M.W. (Eds). Toulouse. France, 1996. Pp. 19-30. Venational homologies and nomenclature in Chrysopidae, with comments on the Myrmeleontoidea (Insecta: Neuroptera) Phillip A. ADAMS California State University, Fullerton, U.S.A. ABSTRACT Fossil history and studies of comparative morphology have largely corroborated the interpretation of venational homologies in Chrysopidae advanced by TILLYARD (1916b), based on pupal tracheation. Despite difficulties in identifying terminal branches of the Posterior Median (MP) and Anterior Cubitus (CuA), it is shown that the latter is multibranched. Venational nomenclature used by SCHNEIDER (1851), NAVAS (1923), and BANKS (1944) are reviewed. Differences in the venation of fore- and hindwings have led to mis- interpretations in both Chrysopidae and Myrmeleontoidea. In the hindwings of Ascalaphidae and Myrmeleontidae the second branch of MP is often mistaken for CuA. Key words: Chrysopidae, Myrmeleontidae, wing venation, pseudomedial, pseudocubital. REVIEW The first comprehensive treatment of chrysopid morphology, by SCHNEIDER (1851), with its detailed system of venational nomenclature, is the starting point of this study. Although the names of longitudinal veins were not yet standardized, nor was the convention of naming crossveins and cells for the vein preceding them, aspects of SCHNEIDER'Ssystem remained in use for nearly 100 years. Neither N. BANKS nor L. NAVAS recognized the existence of pseudomedia (Psm) or pseudocubitus (Psc), and persisted with the terminology they had used before the publication of TILLYARD'S (1916b) paper (Table 1). When these authors mention "cubital cells", or "cubital cells beyond the divisory", they refer to cells distal to the intramedian cell, between Psm and Psc. While this count of cells provides a useful taxonomic character, it may be misleading to the modem worker, who mistakenly might expect "cubital cells" to refer to cells posterior to the "cubitus", between Psc and the posterior margin of the wing. Ph.A. Adams Table 1. Chrysopid venational nomenclature. Modern TILLYARD, SCHNEIDER, NAVAS, BANKS, usage 1916 1851 1923 1944 Fore wing Costa Costa Costa Costa Costa Subcosta Subcosta Subcosta Subcosta Subcosta Radius Radius Radius Radius Radius Radial sector (+MA) Radial sector Second Rs R s R s Rs branches - ending on Psm Banksian sectors - Intermediates Intermediates Inner gradates Inner gradates Inner gradates Inner gradates Inner gradates Outer gradates Outer gradates Outer gradates Outer gradates Outer gradates Pseudomedia Pseudomedia First Rs Procubitus Medius Intramedian cell Intramedian cell Areole of cubitus Divisory cell Divisory cell Median cells Median cells - Cubital cells Cubital cells MP2 Median loop Divisory veinlet Divisory Divisory vein branch CuA and Psc Cubitus Cubitus Cubitus Cubitus Pseudocubitus CUP Cubitus 2 Cubital branch Cubital sector - 1A First anal Postcosta Postcubitus - 2A. 3A Anal 2, 3 Forked marginal Axillary veinlet - vein 1, 2 ........................................................................................ Hindwing Psm Pseudomedia Procubitus - Psc Pseudocubitus Cubitus Cubitus - CuA Cubitus 1 Postcosta Postcubitus - ABBREVIATIONS A1, A2 = first and second anal veins dcc = distal cubital cell acsx = apical subcostal cross vein i m c = intramedian cell b = Banksian cell (in Chrysopidae); M A = media anterior = basal piece of MA in forewing NZF = mf = medial fork of myrmeleontoids (in Fig. 5) o = oblique vein, MP2 crossing to b .1 . = Banksian line CuA in myrmeleontoid forewing Bn = Banksian sectors (TILLYARD) o .g . = outer gradate crossveins C uA = cubitus anterior rf = radial fork CuF = cuf = CF = cubitus fork R S = radial sector CUP = cubitus posterior s n = branches of RS (TILLYARD) Icu, 2cu = first, second cubital cell x = crossvein Chlysopid venation COMSTOCK & NEEDHAM (1898-1899) emphasized tracheation as a basis for venational homologies, maintaining that the veins formed around the tracheae, which determined their course. Objections were raised against over-reliance on tracheal information, with WOODWORTH (1906) indicating that there is no apparent difference between veins that are traversed by tracheae and those that are distant from them, that there is great variation in paths taken by tracheae, and that the tracheae form sinuous paths, while the veins make abrupt turns. NEEDHAM (1935) introduced a discussion with "I begin where veins begin, with tracheae", indicating his firm belief in the role of tracheae. HOLDSWORTH (1942) by contrast, showed that in Pteronarcys Newman (Plecoptera), the vein channels appear before the tracheae penetrate the wing pad, demonstrating that the venational pattern is not primarily dependent upon tracheation. TILLYARD (1916b) followed COMSTOCK & NEEDHAM (1898-1899) in the use of pupal tracheation as a basis of venational homologies. He was able to illustrate for the first time the tortuous paths of the veins in both wings of chrysopids (Fig. I), and his system of chrysopid venational terminology, with minor changes, is the basis of that in use today. Recognizing the structural similarity of the Psm and Psc to the undulation of veins giving rise to the Banksian lines (b.1.) of myrmeleontids (Fig. 2), he named the branches of the chrysopid Radial Sector (Rs) which intersect the Psm as "Banksian sectors", and several of the cells between the Psm and Psc as "Banksian cells". In addition, he accurately noted the extent of CuA and its branches, after its junction with Psc, and in the hindwing the origin of the Psc from the stem of the second branch of MP. Moreover, he correctly analyzed the venation of the Apochrysinae. Fig. 1. Tracheation of pupal wings of Mallada signata (Walker). Note difference in paths of "M2" (MP2) and "Cul" (CuA) in fore- and hindwings, zig-zagging and overlap in tracheae forming Psm and Psc. From TILLYARD (1916b). Fig. 2. Wing venation of Nrsydrion nigriner.i#e Esben-Petersen (Nyrnphidae). The medial fork MF of the hindwing is configured similarly to the cubital fork CF of the forewing; the anterior cubitus CuA of the hindwing is reduced and concave. Arrows indicate the boundary between medial and cubital systems. From ADAMS (1958). COMSTOCK (1918) reviewed the earlier literature on wing venation, and presented a standard system of venational nomenclature for all insect orders, based largely on studies of the development of wing tracheation. Despite its shortcomings, the COMSTOCK- NEEDHAM system of venational nomenclature is still in use. He largely followed TILLYARD'Snomenclature for the Chrysopinae, and presented a drawing of chrysopine pupal tracheation by R.C. SMITH. In the absence of pupal apochrysine material, he unsuccessfully attempted to analyse the complex venation of Apochrysa Croesus Gerstacker as a representative of the Apochrysinae. He noted the absence of the intramedian cell and, in the hindwing, the origin of the apparent pseudocubitus (Cul) from the posterior branch of the median (M), as in the myrmeleontoids. COMSTOCK (1918) failed to recognize the presence of a Psm and Psc, as well as not observing the similarity in origin of the Psc in the hindwings of Chrysopinae and Apochrysinae and, despite having seen TILLYARD's (1916b) paper, he erroneously concluded that the wings of "Apochrysidae" were closely analogous to those of Myrmeleontidae. The work of ADOLPH (1879) was reviewed by COMSTOCK (1918) and will not be discussed here. LAMEERE (1923) and MARTYNOV (1930) revived ADOLPH'S emphasis on convexity and concavity of wing veins as an aid to determining homology, detecting the presence of an anterior branch of M, fused basally with Rs in living insects. In Neuroptera, MA is more obvious than in most orders, appearing as a convex branch from Rs and often, in Osmylidae and the myrmeleontoid families, MA is more extensively branched than the branches of Rs, occupying a triangular area termed the "radial cuneate area" (COMSTOCK 1918). In the hindwings of several families, excepting Chrysopidae, MA is connected to MP by a sinuous, nearly longitudinal vein, which is probably the basal piece of MA. Where venal fusion is more obvious, such a sinuous formation is quite usual (e.g. KUKALOVA-PECK 1991: fig. 6, 27 H, hindwing). In the forewing, various crossveins have unconvincingly been suggested as the basal piece of MA by CARPENTER (1940). Chrysopid venation The LAMEERE-MARTYNOV approach has been extended and applied to fossil as well as extant insects by KUKALOVA-PECK (1991), who maintains that each of the veins consists of convex anterior, and concave posterior branches, and finds evidence of this condition in the precosta, costa, and subcosta, as well as the other main veins in the most archaic insects. In the hindwings of Neuroptera, convexity-concavity appears to be reversed in MP2 which is convex, and CuA, which becomes a concave vein (ADAMS 1958). KUKALOVA-PECK (1991: fig. 6,27 H) interprets the venation of Varnia Walker (Ithonidae) as having undergone fusion of CuA and MP, CuA retaining its convexity after separating from MP distally. But, in that case, the entire CuA is fused with MP. In the ithonid Oliarces Banks, CuA is a concave vein which does not coalesce with MP, as in other Neuroptera. Fossil evidence The well-preserved wings of the pre-nothochrysine Protochrysa aphrodite Willrnann & Brooks (Fig. 3), from the early Tertiary, afford the opportunity to examine a venational

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