432

Behningiidae MOTAS¸ & BˇACESCO, 1937

A small family consisting of 3 genera and 6 extant Peters & Peters (1977, Int. Rev. Ges. Hydrobiol. 62: species including a single representative in Europe. 409). Behningiidae are characterized by the following apo- Behningiidae had been originally proposed inde- morphies (cf. also Edmunds & Traver 1959, McCaf- pendently by Mota¸s & Bˇacesco (1937, Ann. Sci. ferty 1991, Peters & Gillies 1991, Kluge 2000, Univ. Jassy 24, 2: 27) and Tshernova (1938, Izv. 2004): In larvae head, thorax and abdominal projec- Akad. Nauk SSSS, Ser. biol. 1: 129). At the same tions of a unique shape covered with posteriorly di- time, Lestage (1938, Bull. Ann. Entomol. Belg. 75: rected stout and strong bristles. Frons with a pair of 346) placed Behningia in the family Oligoneuriidae. wide rounded projections covering also bases of an- Subsequently Mota¸s & Bˇacesco (1940, Ann. Scient. tennae, mouthparts adapted to predatory habits: Univ. Jassy 26, 3: 78) considered Behningia to rep- mandibles shortened, incisors stout with molar portion resent a separate subfamily within Oligoneuriidae, reduced, glossae and paraglossae small, labial palps while Demoulin (1952, Bull. Inst. Roy. Nat. Belg. 28, enlarged, massive and without muscles inside segment 21: 1) restored family status. Edmunds & Traver 2. A “fish-basket”-like structure is formed by the hy- (1959) clearly defined the placement of the Behningi- popharynx (superlinguae and bristles along their inner idae in the superfamily and McCafferty margin). A pronotal crest separating the collar devel- (1991, Ann. Entomol. Soc. Amer. 84: 349) proposed oped in the form of large, flat, posterolateral projec- the monotypic superfamily Behningoidea. tions densely covered with stout bristles. Abdominal terga with a pair of longitudinal ridges with similar Behningia LESTAGE, 1929 bristles, sometimes covering gills. Imagines have a Behningia LESTAGE, 1929; Bull. Ann. Soc. Entomol. very short life span, and imaginal stage is suppressed Belg. 69: 436 in females (mating and oviposition in subimaginal stage). Non-functional middle and hind legs of = (tarsi Type species Behningia ulmeri LESTAGE, 1929 by lost, not segmented in fore legs) and all legs of R ves- monotypy. tigial. Leg abscision has been observed in (cf. DIAGNOSIS. Larvae are characterized by ovoid-shaped Peters & Peters 1986, Florida Entomol. 69: 246). In galeolacinia, length ratio segment 1 : 2 of labial palps fore wings, vein RSa simple, not forming a triad. Cu- 2 1.5 : 2. Tibiae of hind legs reduced, tarsi of fore legs bital membrane with 1-8 intercalaries, vein CuA sim- not fused to tibiae, claws absent. In imagines geminate ple or bifurcate. Amphitornal margin of imaginal vein pairs are present in fore and hind wings. Fork of wings with setae similar to subimago. Penis lobes very vein CuA well developed. Segments of forceps partly long, forceps lack distal segments, paracercus strongly fused, penis lobes tubular, less than 1.5 times longer reduced (see Kluge 2004: 243 for details). Larvae are than forceps. highly specialized, burrowing in shifting sand biotopes and feeding on small benthic invertebrates. Imagines LARVA. Head, thorax and abdominal projections cov- crepuscular, exhibiting highly synchronized mass ered with paired groups of posteriorly directed stout emergence, females occurring sometimes in two and strong bristles. Labrum roughly oval, about 4 colour morphs (pale and dark ones in Dolania). Dis- times broader than wide, with lobe-like lateral parts tribution Holarctic and Oriental, with very restricted, and small incurvation in the middle of fore margin. relict areas in Europe, Russian Far East and Thailand Molar part of mandibles without teeth, only bristles of (Behningia LESTAGE, 1929), Southeastern United different shape and length present. Superlinguae of States (monotypic Dolania EDMUNDS & TRAVER, hypopharynx oblong-shaped, lingua about twice 1959) and Far East and Thailand (Protobehningia broader with concave anterior margin. Maxillary palp TSHERNOVA & BAJKOVA, 1960; 2 species). 3-segmented: segment 1 very large, oval-shaped, seg- The family is well characterized and a cladistic ments 2 and 3 long and narrow, flagellate, with a reg- analysis at genus level has been presented by Peters ular longitudinal row of bristles. Glossae and para - & Gillies (1991, Overviews & Strategies Ephemer. glossae almost entirely fused. Labial palp stout, 3-seg- Plecopt., p. 216). Genera have been keyed by Peters mented. Hind femora strongly expanded, about 1.5 & Gillies (1991), most Old World species by Tsher- times longer than wide, bidentate at apex. Hind tibia nova (1940, Zhizn Presnykh Vod SSSR 1: 130), very short, somewhat crooked, almost hidden under Tshernova & Bajkova (1960, Entomol. Obozr. 39: femur. Hind tarsus fused, rod-like, narrow and about 415), Tshernova et al. (1986: 111) and Kluge (1997: twice longer than tibia. Tarsal claw missing on hind 214). and biology of the single Nearctic legs. Seven pairs of abdominal gills with fringed mar- species have been treated by Edmunds & Traver gins. Gill 1 simple, about 3-4 times longer than gill 7 (1959, Ann. Entomol. Soc. Amer. 52: 46), McCaf- in younger nymphs, still distinctly longer in fully grown ferty (1975, Trans. Amer. Entomol. Soc. 101: 451), nymphs. Cerci and paracercus present. BEHNINGIIDAE 433

IMAGO. Compound eyes of male large, spherical or Zool. 69: 1092) for further details of oogenesis, fe- oval and strongly convex, not contiguous. In female cundity and possible explanations of this phenome- imagines eyes distinctly smaller. Fore wings triangular, non. less than twice longer than broad, posterior margin AXONOMY. Within Behningiidae, the genus Behnin - convex or slightly undulated, fork of vein CuA well de- T gia is clearly separated by the ovoid arrangement of veloped. The following pair of longitudinal veins gem- galeolacinia (not ovoid in Protobehningia and Dola- inate: RSa +iRS, RSp+Ma , iMA+MA , MP +iMP, 2 1 2 1 nia MP +CuA (Kluge 2004: 246). Similar but less pro- ), length ratio of segments of labial palps 1.5 : 2 2 Protobehningia nounced gemination also in hind wings. Cross veins (segments of equal length in and Dolania usually week or missing, irregular small fields may be ), tibiae of hind legs reduced (not reduced in Protobehningia formed especially in some fore wing membranes. For- ), tarsi of fore legs not fused to tibiae Protobehningia ceps base with wide, U-shaped incision on anterior (fused in ), claws on hind legs absent Protobehningia margin. Basal segment of forceps fused with forceps (well developed in ) in larvae. In imag- Behningia base. Segment 2 of forceps bent or slightly S-shaped, ines is characterized by geminate veins (not Protobehningia Dolania apical part nearly straight. Penis lobes separated geminate in and ), fork of Protobehningia nearly from the base, tubular, long and straight, ex- vein CuA well developed (lost in ), Proto- ceeding forceps length almost by ½. basal forceps segments fused (separated in behningia), shape of segment 2 of forceps (distinctly DISTRIBUTION. Palaearctic and Oriental, from eastern hooked in Protobehningia and Dolania) and penis Europe (B. ulmeri) to the Far East of Russia (B. tsher- lobes less than 1.5 times longer than forceps (more novae), the Amur Basin (Tshernova 1938, 1952) and than twice longer in Protobehningia and Dolania). Primoriye region (Tshernova et al. 1986, Tiunova See also Peters & Gillies (1991) and Kluge (2004) for 1997, Far Eastern Entomol. 9: 1) with an extension details. According to a cladistic analysis of 9 key char- into South East Asia, Thailand (B. baei) (Parnong et acters of both larvae and imagines by Peters & Gillies al. 2002, Science Asia 28: 407). (1991) Behningia and Dolania represent a sister group sharing mainly the arrangement of forceps and BIOLOGY. Larvae of the burrowing type, restricted to legs in larvae. Behningia is considered to represent lowland rivers and living exclusively in sandy habitats the more apomorphic condition (geminate veins). The (psammal). Larvae carnivorous (engulfers) with well genus Protobehningia represents a sister group to apparent adaptation of mouthparts. The functional Behningia + Dolania. An annotated key to recent morphology of mouthparts has been discussed by species of Behningiidae (larvae and male imagines) Elpers & Tomka (1994, Arch. Hydrobiol., Suppl. 4: has been provided by Hubbard (1994, Great Lakes 381-413). Further adaptations in the alimentary sys- Entomol. 27, 3: 161-168), diagnostic characters of tem include stomodeal crop in prothorax (Soldán Behningia larvae have been further discussed by Mc- 1978, Ann. Entomol. Soc. Amer. 72: 636, Landa & Cafferty & Jacobus (2006). Molecular taxonomy of Soldán 1985, Studies Czechoslov. Acad. Sci. 1985, Behningia sp. has been studied by Ogden & Whiting 4: 99). Imagines crepuscular, with early morning (Molecular Phylogen. Evolut.37: 625). emergence before sunrise and highly synchronized mass swarming once a year. Life cycle unknown in REMARKS. Behningia lestagei was described on the detail, larval development requiring presumably more basis of a single R larva (Mota¸s & Bˇacesco 1937). than one year as suggested by Keffermüller (1957, Morphological differences, if any, are minute and the 1959, 1960) and Landa (1969: 295). In Poland, type material of B. lestagei is most probably lost. Va- adults of B. ulmeri have been observed to fly in June. lidity of Behningia lestagei has been discussed by In the Far East (Amur River) male imagines of B. Mota¸s & Bˇacesco (1940, Ann. Scient. Univ. Jassy tshernovae have been collected end of July and ma- 26: 78, figs. 1-4, pl. 1), Demoulin (1952: 28, 21: 1), ture larvae in the first decade of August (cf. Kluge Demoulin (1955, Bull. Ann. Soc. Roy. Ent. Belg. 91: 1995). Reproductive strategy of Behningia and Dola- 207), Keffermüller (1957, Frag. Faun 7: 254), Kef- nia is quite unusual among , producing a very fermüller (1959, Poz. Towar. Przy. Nauk 19, 5: 8, pl. small number of very large eggs. Fecundity of about 4-7, 9-12), Edmunds & Traver (1959, Ann. Entomol. 70-100 eggs per female is approximately 21 times Soc. Amer. 52: 46, figs 13-23), Tshernova & Bajkova less than in other taxa, the eggs (about 1,0 mm (1960, Entomol. Obozr. 39: 410), Keffermüller in length) are the largest known among (1963, Bad. Fizj. Polska Zach. 12: 323), Koss & Ed- Ephemeroptera. Due to the extraordinarily high munds (1974, Zool. J. Linn. Soc. 55: 324) and Peters amount of yolk, first instar larvae (larvulae) are well & Peters (1986). Peters & Gillies (1991, Overview developed and about 2.5 - 5 times longer than any Strategies Eph. Plec. p. 216, figs. 12, 13) provided a other mayfly larvula. Second instar larvae are already drawing of the imaginal wings of B. ulmeri (origin of predaceous (Tsui & Hubbard 1979; Hydrobiologia, material not stated) differing from drawings by Keffer- 67, 2: 119-123). See also Fink et al. (1991, Can. J. müller (1959: 319, Tab. IV, fig. 1; sub ? B. lestagei)