An Illustrated Review of Egg Morphology in the Families of Neuroptera (Insecta: Neuropteroidea)
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P P P p-p P - - - - - - P - - P P Advance5 In Neuropterology Proceedings of the Thlrd International Sympos~umon Neuropterology Berg en Dal. Kruger Ndtlonal Pdrk, R S A , 1988 Mamell, M W 81 Aspock, H (M\) Pretoria, R S A 1990 Pp 131-149 - - - pp p - - - - P - - -- An illustrated review of egg morphology in the families of Neuroptera (Insecta: Neuropteroidea) Johann GEPP Institut fiir Umweltwissenschaften und Naturschutz. Graz, Austria ABSTRACT Thc eggs of 112 species representing 15 families of Neuroptera are listed, and a review summarizing data in 85 references is provided. The external n~orphologyof the eggs is depicted in 12 photographs and 12 drawings, whilst 20 scanning electron micrographs provide details of the micropylar and surface structures. Key words: Eggs, morphology, Neuroptera, Ascalaphidae, Berothidae, Chrysopidae, Coniopterygidae, Dilari- dae. Hernerobiidae, Ithonidae, Mantispidae, Myrmeleontidae, Nernopteridae, Nymphidae, Osmylidae, Poly- stoechotidae, Psychopsidae, Sisyridae. INTRODUCTION Morphological details of the eggs of Neuroptera have been discussed by several authors, particularly Withycombe (1925), Killington (1936, 1937), Balduf (1939), Popov (1 973), Hinton (1981) and New (1986). Whilst the eggs of a few families of Neuroptera, especial- ly Chrysopidae, Hemerobiidae and Ascalaphidae, are well known, only a few detailed descriptions of the egg-stage of most other families are available. The eggs of the families Brucheiseridae, Rapisniatidae and Neurorthidae are still unknown. This contribution presents an illustrated review of present knowledge of the eggs in the families of Neuroptera. Gepp (1984a) recently provided a literature review of thc known larval stages of Neuropteroidea. GENERAL MORPHOLOGY OF NEUROPTERAN EGGS The eggs of most Neuroptera are oviform and one and one half to two times longer than wide. Spherical eggs are only known in the family Nemopteridae, and almost spherical eggs are found occasionally in the families Myrmeleontidae (Figs 41, 42), Ascalaphidae (Figs 14, 18) and Psychopsidae (but see also Fig. 16). Elongated eggs (two to four times longer than wide) are found in the Coniopterygidae (Fig. 2), Osmylidae (Fig. 1l), Dilari- dae (Fig. 15) and sometimes in Myrmeleontidae. Eggs with pointed micropylar regions are known in Drep.parzepteryx phuluetzoides Linnaeus (Fig. 19), in the genus Italochrysa Principi (Fig. 30), Psychopsis elegans Guerin (Fig. 16) and in some Coniopterygidae, J. Gepp e.g. Senridalis czleyrodiformis Stephcns (Gcpp & Stiirzer 1986). The lengths of the eggs vary horn less than 0,4 mm (Sisyridae, Mantispidae) to 5,5 mm and more in Myr- meleontidae. Due to adhesion to the substrate, the underside of the egg may be flat in most species of Coniopterygidae, Osmylidae and Hemerobiidae. As far as is known, all Nymphidae, Mantispidae and, with few exceptions each, Chrysopidae and Berothidae lay their eggs on secreted stalks. Eggs of Myrmeleontidae and Ascalaphidae have two micropyles and the eggs of the remaining families one each (Fig. 19), which are more or less charac- teristically shaped (Figs 25, 26). The structure of the chorion seems to be species-specific in the varioi~sgroups, but extensive and careful comparative studies are still needed. The eggs of most central European species can be distinguished by their specific chorions, with the aid of scanning electron micrographs (Gepp, unpublished data), and the species examined are listed by Gcpp (1986). Papilla-shapcd (Chrysopidae, Figs 35-38; Myrmcleon- tidae, Fig. 43; Dilaridae, Fig 44) or sponge-like elevations (Hemerobiidae, Fig. 24) as well as net-like patterns (Coniopterygidae, Figs 1-4; Dilaridae, Fig. 15 and Nemopteri- dae, Fig. 17) have been observed. The surface of the eggs may be covered in substrate particles adhering to the egg as is the case in some Myrmeleontidae (Fig, 41), Ithonidae and Psychopsidae, or by hairs from the female as in some Sisyridae (Fig. 12). Egg-breakers invariably occur in the families Coniopterygidae (Figs 1,2) and Hemerobiidae (Figs 21,22) but have never been observed in others, e.g. Myrmcleontidae and Ascalaphidae. REVIEW OF THE FAMILIES Coniopterygidae Species with described eggs: Coniopteryx exigua Withycombe ( = pusana Withycombe): Narayanan 1942 Coniopteryx parthenia (Navas & Marcet): Killington 1936 Coniopteryx tinefirmis Curtis: Killington 1936; Figs 1, 3 Coniopteryx califorrzica Meinander ( = hageni Banks): Quale 19 12 Conwentzia pineticola Enderlein: Collyer 1951 Conwentzia psociformis (Curtis): Figs 2, 4-6 Conwentziu sinica Yang: Yang 1974 Parusemidalis fuscipennis (Reuter): Withycombe 1923a Semiclnlis albata Enderlein: Yang 195 1 Semidulis aleyrodiformis (Stephens): Killington 1936; Gepp & Stiirzer 1986 Semidalis vicinu (Hagcn) : Muma 1967 The Coniopterygidae have mainly elongated eggs (Figs 1 & 2) which, in most cases, arc whitish or reddish initially but may also be green, grey or darkly-coloured. The chorion may manifest various patterns (Figs 3 & 4), whilst the micropyle (Fig. 5) and fine struc- tures (Fig. 6) provide species-specific characters with the aid of a scanning electron micro- scope. The bottom is flat or adapted to the surface. Empty cgg shells are white. Ithonidae Species with described eggs: Ithone&.scu Newman: Tillyard 1922; Withycombe 1925; Riek 1970 Oliarces clarc1 Banks: (Faulkner, unpublished data) The eggs of I. &sca (Fig. 7) arc deposited in sand or loose on the surface (sizc: 1,7 X 0,9 mm), and the number of eggs laid by a single female varies from about 200 to almost Egg morphology in Neuroprera Fig- I -t~. SEL1 (1 t tg;c 131 tl~c l;~rni[yC'on~uptcrycrtl,ic.: I . C;c.r~cr;ll view II~egg-hhcll of Cor~rtrytt.r?:rtitltifi>rrr~i, CurIir (Icnpth 0.5 1 nlnl): 2. Gcncriil view uf an cpy-shelt ofCorrn~er~r:ta psnrifnr- IIII.~(Cunis) (Icnglh (1.5? rnlub; 3, Hnneyrcrrlth pattern (>Cur! cgg of C. rirrr,ifi>rrr~is:4. Honcycrrmh pallcm of an cgg of C. />.corililrn~i.r-:5. MlcropyEc ol' an egg or C. p.~,sric~fnrx~ris;h. Chr>rionic niicro-pattern of a lioneycornh of an cgf nf C, p.cr>rifi~rt~ris. Figs 7-10. Oviform egg-types of the families (frorn left to right) Ithonidae, Osmylidae, Polystoechotidae and Sisyridae: 7. Eggs of lrhont~,fisc.aNewman (length 1,7 mm), the surracr is quite smooth, creamy-white, without sculpturing but covered with sand and soil particles after laying ((redrawn from Tillyard 1922); 8. Egg of S~c,nosmylu.s fenuis (Walkcr) (length 0.85 rn~n),pale ycllow when fresh, darkening to pale-brown then dark-brown heforc hatching (redrawn from New 1974); 9. Egg of Poly- .storchorrspuncmtus Fabricius (length 0.93 mrn), the surface is ~moolhand free of surface structul-es (hut ~ninutelygranular), chalky-white, later green (rcdrawn from Hungcrford 193 I); 10. Egg of Clirncrc.in cir.eo1uri.c (tfagen) (length 0.34 mm), is glistening, whitish and wnii-tranrparent when frehhly laid (drawn from a photo by Brown 1952). 300. The anterior end of the egg bears a raised disc-like micropylar knob. The surface is quite smooth, without visible sculpturing, but coated with sand. Faulkner (pers. comm.) knows the eggs of another undescribed North American species, which are laid close together in sloping rows; the micropyles are white, the egg shells colourless and translucent. Osmylidae Species with described eggs: 0.srrlylu.s fulvicephulus (Scopoli): Withycombe 1925; David 1936; Killington 1936; Ward 1965 St~rlosmylustenuis (Walker): New 1974, Fig. 8 The eggs of 0. &lvicephalu~ are relatively large and are laid on the upper surfaces of leaves (Fig. 11). The eggs are attached to the substrate by their flat side and are laid in close contact, side by side, to form a straight or slightly curved row. They are rarely laid singly.Withycombe (1925), Killington (1936, 1937) and New (1974, 1986) provide fur- ther information on this family. Polystoechotidae Species with described eggs: Polptoechntes punclatus Fabricius: Welch 19 14; Withycombe 1925; Hungerford 193 1. The eggs of P. punctutus are laid singly, they are stalkless, ovoid (O,9 X 0,s mm), chalky- white with a fincly granular surface (Welch 1914) and each with a button-like micropyle (Fig. 9). Sisyridae Species with described eggs: Climacici arcoluris (Hagen): Brown 1952 Slcjm fi.sca (Fabricius): K~llington1936 Sr~xrcrterrnintili.\ Curtis: Withycombc 1923a, 1925 Egg morphology in Neuroptera Sisyridae lay very small eggs in small clusters in depressions, especially along the veins of leaves overhanging water. The egg of S. fi4.sc~ru is elongate-oval (length 0,35 mm) and bears one ~rlicropylarknob; the female occasionally deposits some hairs on the egg (Figs 10 & 12). Berothidae Species with described eggs: Lorriutnyia .fluvic-(1rni.s(Walker): Smith 1923 Lornurtiyia lalipctznis Carpenter: Toschi 1964; Tauber & Tauber 1968 S~~crrnophor~lludi.sseminatu Tillyard: Tillyard 19 16 S1)erinophorella rnuci~htissimaTillyard: T~llyard19 16 The eggs of S. disscminutu are deposited on stalks: several batches of such eggs were found, ranging fio~n30 to 50 eggs each, which closely resembled the fruiting bodies of small clulnps of moss. The stalk is hollow throughout except at the base and tip. and is so delicate that it sometimes bends under the weight of the egg (Fig. 27) (Tillyard 1916). The eggs of L,. lutipentzis are also stalked and are laid in small clumps comprising fewer stalks than eggs (Fig. 28) Toschi 1964. Tauber & Tauber (1968) report that the stalks are apparently very flexible and do not support the eggs as do those of the eggs Chrisopidae, but serve to suspend the eggs from a substrate. Smith (1923)