Evolution and Success of Antlions (Neuropterida: Neuroptera, Myrmeleontidae)

© Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at Evolution and success of antlions (Neuropterida: Neuroptera, Myrmeleontidae) Mervyn W. MANSELL Abstract: and hold the key to the unresolved higher classification of Myrmeleontidae. Additio- Myrmeleontidae comprise the largest nal information is also forthcoming from and most widespread family of Neuroptera historical biogeography. Classifications, owing to their ability to exploit a wide ran- morphological adaptations, life histories, ge of habitats including sand. A psammo- predation strategies and distribution pat- philous existence was facilitated by sever- terns are reviewed and discussed as a con- al larval autapomorphies in the ground- tribution to elucidating relationships with- plan of Neuroptera that pre-adapted antlions to a life in sand and ensured their in the Myrmeleontidae. evolutionary success. The progression Key words: Myrmeleontidae, higher from arboreal habitats to psammophily classification, subfamilies, evolution, bio- may reflect the phylogeny of the family geography, biology, psammophily. Stapfia 60. zugleich Kataloge des OÖ. Landesmuseums, Neue Folge Nr. 138 (1999), 49-58 49 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at Introduction tion that set Neuroptera on an evolutionary course and engendered a remarkable order of Myrmeleontidae are a highly evolved predatory insects. Enigmatically, this speciali- family of Neuroptera whose larvae have adop- sation was not restrictive, but resulted in the ted a variety of predation strategies that ena- radiation of Neuroptera into an impressive ble them to exploit a wide range of habitats array of morphologically and biologically relative to other families. This versatility has diverse taxa that comprise 17 families. It also ensured their evolutionary success as the lar- provided a larval autapomorphy to underpin gest and most widespread group, rivalled only the monophyly of Neuroptera, and established by Chrysopidae, in the neuropteroid lineage. them as a highly effective functional group of There are currently about predators. 2000 described species of ant- Myrmeleontidae, in particular, have lions distributed throughout exploited the specialised larval mouthparts the world, but especially in the that pre-adapted them to a variety of habitats, arid regions of the globe culminating in psammophily (Fig. 2). This (ASPÖCK H. et al. 1980). was the key to the evolutionary success of ant- Many of these species names lions. Occupation of different habitats enab- are synonyms, but they are led these „sit and wait" ambush predators to being offset by new discoveries develop many tactics to improve their effi- that will eventually yield a far ciency as predators. These range from lurking higher number of extant taxa. camouflaged on rocks and vegetation, in tree- The family also includes some holes, concealed in dust and sand, under rock of the largest and most striking overhangs, in animal burrows and ultimately oi all insects, with wingspans the ability to modify the immediate sandy ranging from 30-170 mm. environment into traps. Many have ornately patterned The abundance of antlions and their vor- wings (Fig. 1) that enhance acious feeding habits are an important influ- the camouflage and cryptic ence in the regulation of populations of gro- behaviour of these great in- und-dwelling and arboreal arthropods. In arid sects. areas such as the Kalahari savannah of sou- The range of habitats and thern Africa, the biomass of large predatory predation strategies reflect larvae of Palparini (Figs 3-5) and other tribes evolutionary trends within the could well exceed that of vertebrate predators. Myrmeleontidae, from plesio- Larval and adult antlions, in turn, are a morphic arboreal habitats to sustainable food resource for invertebrates and the apomorphic occupation of vertebrates in natural ecosystems. Many spe- sand. This was facilitated by a cies are restricted to specific habitats and bio- unique morphological adapta- mes, and are sensitive to ecological disturbance, Fig. 1: Palpares speciosus (LINNAEUS), Western Cape Province, South Africa. Length = 70 mm Fig. 2: Larva of Crambomorphus MCLACHLAN, Kalahari Savannah, South Africa, displaying the psammophilous habit. Length = 30 mm. 50 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at Fig. 3: Larva of Golafrus oneili (PERINGUEY), Kalahari Savannah, South Africa. Length = 35 mm. (Photo: A.S. Schoeman). Fig. 4: Larva of Crambomorphus MCLACHLAN, Kalahari Savanna, South Africa. Length = 30 mm. Fig. 5: Larva of Palpares annulatus STITZ, Kalahari Savannah, South Africa. Length = 25 mm. (Photo: R.G. Oberprieler). rendering them excellent bio-indicators of the attention of scientists since early times, environmental degradation. This is of particu- and are entrenched in folklore (WHEELER lar concern in South Africa where large-scale 1930, KEVAN 1992). Despite this, the global habitat fragmentation and application of systematics and phylogenetic relationships of pesticides threaten several endemic populati- Myrmeleontidae remain obscure owing to the ons such as the vulnerable genus Pamexis dynamic evolutionary state of the group and HAGEN (Fig. 6). Apart from their obvious bio- the consequent plethora of synonyms in the logical significance, Myrmeleontidae are ideal literature. These issues are currently being subjects for the study of insect behaviour, phy- addressed by several researchers, and some siology, biogeography and evolution, and is phylogenetic analyses have already been car- consequently a group that urgently warrants ried out (e.g. MANSELL 1992, STANGE 1994). study and conservation. Various authors have attempted to arrange Antlions and their habits have captured the Myrmeleontidae into subfamilies, tribes 51 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at and subtribes, but no consensus has been rea- TlLLYARD (1916) recognized Banks' two subfa- ched, as most classifications lack a sound phy- milies and added two more tribes in studies on logenetic basis. The variety of lifestyles and the Australian fauna. EsBEN-PETERSEN (1918) biogeography of antlions may, however, reflect divided the Myrmeleontidae into two sec- evolutionary trends within the family that tions, Archaemyrmeleonida and Neomyrme- could contribute to resolving their higher clas- leonida, the former including only the Palpa- sification. The current paper consequently nni, and the latter comprising the Myrme- reviews information on supra-generic classifi- leontinae with four tribes and Dendroleon- cation, morphology, biology and historical tinae with six. BANKS (1927) raised the Palpa- rini and Macronemurini to subfamily status and added two more tribes, and subsequently- elevated the Acanthaclisini to subfamily level (BANKS 1943). More recent contributions have been tho- se of MARKL (1956) who classified the genera of the world into 23 tribes, adding 10 new tribes in the process. He did not mention subfamilies in his treatise, but it had had the important effect of focussing attention to the higher classification of Myrmeleontidae, and provi- ding a basis for future discussions. STANGE (1961) mentioned three subfamilies, Acant- haclisinae, Macronemurinae and Dendroleon- tinae, but did not deal with Myrmeleontinae or Palparinae. In 1967 and 1970a, STANCE referred to four subfamilies, omitting Macro- nemurinae, and then (STANCE 1970b) synony- mized Dendroleontinae and Macronemurinae with Myrmeleontinae. HöLZEL (1969) established the tribe Isoleontini, and in 1970 he also included the tribes of Dendroleontinae in Myrmeleontinae. RlEK (1970) placed the Aus- Fig. 6: Pamexis karoo MANSELL, Karoo biogeography, particularly vicariance events, National Park, South Africa. Wing tralian Myrmeleontidae in four subfamilies, length = 34 mm as a contribution to elucidating the phylogeny Dendroleontinae, Macronemurinae, Acant- and classification of the family. haclisinae and Myrmeleontinae, but did not mention tribes. HöLZEL (1972) recognised three subfamilies, Palparinae, Myrmeleon- tinae and Echtromyrmecinae, and STANGE (1976) listed Acanthaclisinae, Palparinae and Higher classification of Myrmeleontinae. WILLMANN (I977) and Myrmeleontidae ASPÖCK H. et al. (1980) reduced the number of subfamilies to two, Palparinae and Myrme- Supra-generic classification of Myrme- leontinae, but the latter did not provide a tri- leontidae was initiated by BANKS (1899) who bal classification. NEW (1982) relegated the distinguished two groups, Myrmeleoni and family Stilbopterygidae to subfamily status, Dendroleoni. In his study of African antlions assigning Albardia VAN DER WEELE to the BANKS (1911) elevated these two groups to Ascalaphidae, and Stdbopteryx NEWMAN and the subfamilies Myrmeleoninae and Dendro- Aeropteryx RlEK to the subfamily Stilbop- leoninae, each comprising two tribes, Palpari- teryginae within Myrmeleontidae. At this sta- ni and Myrmeleonini and Dendroleoni and ge some consensus appeared to be emerging Nemoleonini respectively. regarding subfamilial classification, but none NAVAS (1912a, 1912b, 1913, 1914a, of these subfamilies was based on sound phy- 1914b, 1926) added eight more tribes, while 52 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at logenetic characters, and still require apprai- modification of the malpighian tubules for silk sal. The tribes were also subjectively defined production and cryptonephry (HENNIC 1981). and in considerable disarray, but recently Each of these attributes further

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