Elateriformia (Coleoptera)

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J. F. Lawrence, A. M. Hastings, M. J. Dallwitz, T. A. Paine and E. J. Zurcher

PTILODACTYLIDAE

(= Dascillidae part).

Classification. Polyphaga: Elateriformia.

Distribution. Ptilodactylidae occur in most areas of the world, but have no endemic species in Europe. Araeopidius monachus (LeConte) (Araeopidiinae) occurs in the northwestern part of North America from Alaska south to central California. Ptilodactylinae occur in most parts of the world, especially in warmer regions, and one species is known as a greenhouse pest in Italy (Süss and Puppin 1976).

Biogeographic regions: Nearctic, Palearctic, Neotropical, Afrotropical, Oriental, Australian.

Biology. With some exceptions, Ptilodactylidae live in riparian, semiaquatic and aquatic habitats, and their larvae often have various adaptations for survival under water, such as anal gills or a spiracular siphon. Adults are often collected on riparian vegetation or in flight-intercept traps. In some groups (e.g. Daemon, Aploglossa) they have maxillary brushes for feeding on surface microfungi. Larvae of Araeopidius monachus live among rocks and gravel in and adjacent to streams and rivers. They probably feed on dead plant material, and have special adaptations (plastron plates) to survive flooding. Ptilodactyline adults are often found on foliage and feed on microfungi; their maxillae are modified to form brushes for handling spores and loose hyphae; their larvae occur in leaf litter or dead wood, often in wetter environments. Unlike some other members of the family, these larvae do not have special adaptations for surviving under water.

Notes. This family is badly in need of a complete revision, which could have to involve a study of related families, such as Eulichadidae, Cneoglossidae, Psephenidae, Chelonariidae and Podabrocephalidae. Five subfamilies are listed by Lawrence and Newton (1995): Anchytarsinae, Cladotominae, Aploglossinae, Araeopidiinae and Ptilodactylinae. It is likely that Ptilodactylinae is a monophyletic group based on the concealment of the protrochantin and the distinctive type of larva, and both Aploglossinae and Araeopidiinae are monogeneric. It is likely that Cladotominae is paraphyletic, unless both Araeopidiinae and Chelonariidae are included. Anchytarsinae is also probably paraphyletic, unless the tripartite larval submentum is considered to be a synapomorphy at least of those taxa for which larvae are known. In Beutel's (1995) analysis of Elateriformia based on larval characters, Eulichadidae formed a monophyletic group with Ptilodactylidae (Anchytarsus, Byrrocryptus and Ptilodactyla), while Araeopidius and Cladotominae formed a clade with Chelonariidae, Psephenidae, Elmidae, Lutrochidae and Dryopidae. In an analysis of Byrrhoidea (Costa et al. 1999) using both adult and larval characters, Ptilodactylidae formed a monophyletic group with Chelonariidae included. Two internal clades were formed: one with Ptilodactyla, Anchytarsus and Epilichas, and another with Aploglossa (adults only), Araeopidius, the cladotomine genera Cladotoma and Paralichas, and Chelonarium (Chelonariidae).

References

Beutel, R. G. 1995. Phylogenetic analysis of Elateriformia (Coleoptera: Polyphaga) based on larval characters. Journal of Zoological Systematics and Evolutionary Research 33: 145–171.

Costa, C., S. A. Vanin and S. Ide 1999. Systematics and bionomics of Cneoglossidae with a cladistic analysis of Byrrhoidea sensu Lawrence & Newton (1995) (Coleoptera, Elateriformia). Arquivos de Zoologia 35: 231–300.

Guérin-Méneville, E. F. 1843. Note sur un groupe naturel ou une petite tribu des Coléoptères de la famille des Malacodermes. Revue Zoologique 6: 193–194.

Guérin-Méneville, E. F. 1843. Species et Iconographie Générique des Animaux Articules ou représentation des genres avec leur description et celle de toutes les espèces de cette grande division du rêgne animal... I, Coléoptères, Livraison 3, Nos. 10–12.

Guérin-Méneville, E. F. 1849. Species et Iconographie Générique des Animaux Articules ou représentation des genres avec leur description et celle de toutes les espèces de cette grande division du rêgne animal... I, Coléoptères, Livraison 6, Nos. 15, 33, 34.

Lacordaire, T. 1857. Histoire Naturelle des Insectes. Genera des Coléoptères. Tome 4. Libraire Encyclopédique de Roret, Paris, 579 pp., pls. 40–47.

Lawrence, J. F. 1991. Ptilodactylidae (Dryopoidea), pp. 391–394. IN F. W. Stehr (ed.), Immature Insects. Vol. 2. Kendall/Hunt Publishing Co., Dubuque, Iowa.

Lawrence, J. F. and A. F. Newton, Jr. 1995. Families and subfamilies of Coleoptera (with selected genera, notes, references and data on family-group names), pp. 779–1006. IN: J. Pakaluk and S. A. Slipinski (eds.), Biology, Phylogeny, and Classification of Coleoptera: Papers Celebrating the 80th Birthday of Roy A. Crowson. Muzeum i Instytut Zoologii Polska Akademia Nauk, Warsaw.

Lawrence, J. F. and J. B. Stribling 1992. A new genus of Ptilodactylidae (Coleoptera: Elateriformia) from North Queensland, with description of the presumed larva. Journal of the Australian Entomological Society 31: 19–27.

Lewis, G. 1895. On the Dascillidae and malacoderm Coleoptera of Japan. Annals and Magazine of Natural History (6) 16: 98–122.

Pic, M. 1914. Pars 58. Dascillidae, Helodidae, Eucinetidae. IN: S. Schenkling (ed.), Coleopterorum Catalogus. W. Junk, Berlin, 65 pp.

Stribling, J. B. 1986. World generic revision of Ptilodactylidae (Coleoptera: Dryopoidea). Ohio State University (PhD Thesis), Columbus.

Stribling, J. B. 1986. Revision of Anchytarsus (Coleoptera: Dryopoidea) and a key to the New World genera of Ptilodactylidae. Annals of the Entomological Society of America 79: 219–234.

Stribling, J. B. and R. L. Seymour 1988. Evidence of mycophagy in Ptilodactylidae (Coleoptera: Dryopoidea) with notes on phylogenetic implications. Coleopterists Bulletin 42: 152–154.

Süss, L. and O. Puppin 1976. Osservationi sulla morfologia e sulla biologia di Ptilodactyla exotica Chapin (Coleoptera, Ptilodactylidae) nelle serre della Lombardia e contributo bibliografico allo studio del gruppo. Bolletino di Zoologia Agraria e di Bachicoltura (2) 13: 143–165.

General appearance. Total length 2.5–16 mm. Ratio of body length to greatest body width 1.95–2.85. Body slightly flattened to moderately convex, or strongly convex. Sides of body not evenly curved. Body not capable of conglobation (rolling into a ball). Upper surfaces of body glabrous or subglabrous, or clothed with distinct hairs, setae or scales. Vestiture of upper surfaces not including stiff, erect, dark bristles; not including scales or scale-like setae. Upper surfaces of body without deep foveae. Prothorax, metathorax and-or abdomen without extrusible glands. Underside of body without hydrofuge surface(s).

Head. Ratio of head length to its greatest width (excluding eyes) greater than 1, or 1 or less. Head width just behind eyes not distinctly greater than prothoracic width. Head not or slightly declined, or moderately to strongly declined; not entirely concealed from above by pronotum, or entirely concealed from above by pronotum; without elongate rostrum, or with elongate rostrum; not abruptly constricted posteriorly. Temples absent or not closely adpressed to prothorax; absent. Transverse occipital ridge or carina absent, or present. Occiput without stridulatory file. Longitudinal axis of head (from occipital foramen to mouth cavity) inclined at an angle of less than 45 degrees, or inclined at an angle of 45 to 90 degrees. Frontal region not to moderately, gradually declined, or strongly deflexed, vertical or inflexed at apex only. Occipital region without median longitudinal groove or line (endocarina). Frontal region without median groove or line (endocarina). Head without ocelli.

Compound eyes present. Eyes strongly protuberant. Vertical diameter of eye less than 2 times horizontal diameter. Eyes finely facetted; without interfacetal setae. Ommatidium of the exocone type. Eye entire. Anterior or mesal edge of eye not or only barely emarginate. Posterior edge of eye not or barely emarginate.

Antennal insertions exposed from above; moderately to widely separated, or narrowly separated. Antennae not borne on raised tubercles. Subantennal groove or cavity on head absent or very weakly developed. Frontoclypeal suture absent or incomplete, or indistinctly impressed, or distinctly impressed; straight, slightly curved or angulate, or strongly curved or angulate. Clypeus not laterally emarginate. Anterior edge of clypeus or clypeolabrum straight to convex. Mouth cavity anteriorly or anteroventrally oriented. Pregular area without laterally opening cavities. Head ventrally without paired subgenal ridges, or with paired subgenal ridges. Head without anteriorly-projecting genal processes. Gular sutures widely separated or absent, or narrowly separated. Corporotentorium narrow, or incomplete or absent; without median process. Cervical sclerites present.

Antennae. Number of antennomeres 11. Antennae when posteriorly extended reaching beyond middle of prothorax but not middle of elytra, or reaching beyond middle of elytra but not elytral apices. Antennae filiform, or serrate, or pectinate or bipectinate, or flabellate or biflabellate, or with articulated appendages. Antennomeres 3, 4 or 5 to 10 without or with single rami (uniramose). Antennae at least partly pubescent or with obvious modifications. Antennal modifications beginning on antennomere 3 (rarely 2), or antennomere 4. First antennomere (scape) less than 3 times as long as 2nd (pedicel). Antenna not geniculate; without apical club.

Mouthparts. Labrum at least partly visible; free, membranous or separated by suture. Major portion of labrum strongly transverse, or slightly transverse or subquadrate. Apex of labrum subtruncate to slightly convex, or strongly convex, narrowly rounded or acute, or slightly concave or emarginate. Labrum moderately to heavily sclerotized, except at base and-or apex. Mouthparts not forming a piercing or sucking tube, or forming a piercing or sucking tube. Mandibles present. Mandible short and broad, or moderately elongate. Mandibular apex moderately to strongly, gradually curved mesally, or strongly and abruptly curved mesally; unidentate, truncate or rounded, or bidentate or bilobed, or multidentate or multilobed. Dorsal part of mandible without tubercle; without setose cavity. Incisor edge of mandible simple. Mandible with well developed mola, or with reduced mola, or without mola; with well developed prostheca, or with reduced prostheca, or without prostheca. Prostheca absent or without articulated, sclerotized process. Maxilla with distinct galea and lacinia, or with single apical lobe. Maxillary lobe(s) not stylet-like. Apex of galea or maxillary lobe densely setose or spinose; without heavily sclerotized teeth or hooks. Lacinia without hook(s) or spine(s). Apical maxillary palpomere cylindrical to fusiform, or slightly expanded and truncate to subtriangular, or securiform to cultriform; at least as wide as or longer than preapical one. Maxillary palp without complex palp organ. Apical labial palpomere cylindrical to fusiform, or slightly to strongly expanded apically. Ligula undivided or finely cleft, or deeply emarginate or bilobed.

Prothorax. Ratio of pronotal length to greatest pronotal width 0.45–0.82. Prothorax widest posteriorly. Sides of prothorax more or less straight, or moderately to strongly curved, or straight posteriorly, curved anteriorly. Prothorax not laterally compressed to form cavities for legs. Sides of prothorax not or slightly explanate. Base of prothorax not or slightly narrower than elytral bases. Greatest prothoracic width not or slightly narrower than greatest elytral width. Lateral pronotal carinae complete, or incomplete, or absent; simple; visible for their entire lengths from above, or not visible for their entire length from above; without a raised margin, or with a raised margin or narrow bead. Lateral portion of prothorax without deep pit. Pronotum without anterolateral callosities. Anterior angles of pronotum absent or not produced forward; absent, right or rounded, not produced. Posterior angles of pronotum obtuse or right, or moderately to strongly acute; not produced and acute. Posterior edge of pronotum distinctly sinuate or variously lobed; simple, or distinctly crenulate; not or vaguely margined. Discal carinae of pronotum absent. Pronotal disc without paired basal impressions, or with paired basal impressions. Pronotum without median longitudinal groove or line. Hypomeron without pit.

Anterior portion of prosternum at midline shorter than prosternal process, or as long as prosternal process. Lateral portion of prosternum in front of coxae shorter than mid length of procoxal cavity, or as long as mid length of procoxal cavity. Anterior edge of prosternum not produced anteriorly. Prosternum in front of coxae flat to moderately convex, or strongly convex without carina. Prosternum in front of coxae without paired lines or carinae. Anterior edge of prosternum without mesal excavation, or with mesal excavation. Anterolateral or ventrolateral portions of prothorax without cavities or grooves. Prothoracic cavities absent. Prothoracic grooves absent. Prosternal process complete; parallel-sided, or gradually expanded or narrowed and then expanded, or gradually expanded and then narrowed; flat, concave, or only slightly elevated or curved behind coxae, or slightly to strongly elevated but not curved behind; slightly overlapping mesoventrite, or moderately to strongly overlapping mesoventrite. Apex of prosternal process acute or narrowly rounded, or broadly rounded, angulate or truncate. Prosternal process without transverse groove. Accessory (mesal) procoxal articulation absent. Ventral portion of prothorax on each side with notosternal suture only. Propleuron not extending to anterior edge of prothorax. Propleuron or pleurotrochantin not extending behind coxa. Procoxae not or slightly projecting below prosternum, or projecting well below prosternum. Procoxa without or with short concealed lateral extension, or with long concealed, lateral extension. Procoxal cavities present, procoxae countersunk. Procoxal cavity strongly transverse, or slightly transverse. Procoxal cavities at middle narrowly separated. Procoxal cavities externally open; broadly open, or narrowly open. Postcoxal projection absent or very short, or moderately long but not meeting prosternal process. Procoxal cavities without narrow lateral extensions. Procoxal cavities internally open. Prothoracic trochantin or pleurotrochantin at least partly exposed, or completely concealed or absent. Promesothoracic clicking mechanism absent.

Elytra. Elytra present. Ratio of elytral length to greatest elytral width 1.55–2.35. Ratio of elytral length to pronotal length 3.3–4.95. Elytra apunctate, irregularly punctate, or with 5 or fewer distinct puncture rows or striae, or with more than 5 distinct puncture rows, or with more than 5 distinct impressed striae; without scutellary striole. Number elytral puncture rows or striae 11, or 10. Sutural stria absent or not deeply impressed near apex. Abdominal tergites exposed by elytra none or apex of 1. Elytral apices meeting or almost meeting at the suture. Elytral suture not deflected near apex. Elytral apex without internal interlocking tongue. Epipleuron complete; not or gradually narrowed. Lateral edge of elytron straight or weakly sinuate.

Pterothorax. Scutellum well developed; abruptly elevated; anteriorly simple, or notched, or crenulate; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate. Mesoscutum without stridulatory file. Mesoventrite with paired procoxal rests. Paired mesoventral procoxal rests absent, horizontal or slightly oblique. Anterior edge of mesoventrite without prosternal rest. Mesoventrite not divided by longitudinal groove or discrimen, or at least partly divided by longitudinal groove or discrimen. Anterior edge of mesoventrite at midline on same plane as metaventrite. Mesoventral cavity absent, or small and shallow, or moderately large and shallow. Mesocoxa not conical and projecting, or conical and projecting. Mesocoxal cavities present, mesocoxae countersunk. Mesocoxal cavities at middle narrowly separated, or moderately to widely separated. Mesocoxae separated by less than shortest diameter of coxal cavity. Mesocoxal cavities circular to slightly transverse; not or slightly oblique. Mesoventrite separated by complete sutures from mesepisterna. Mesepisterna distinctly separated at midline; without deep pockets. Mesepimeron not visible from above. Mesocoxal cavities open laterally; not partly closed by metepisterna. Mesoventral process extending at least to middle of mesocoxal cavity. Mesometaventral junction a complex fitting.

Metaventral discrimen or median line moderately to very long. Paired postcoxal lines of metaventrite absent. Postcoxal lines of metaventrite absent. Metaventrite longer than first abdominal ventrite. Postcoxal pits of metaventrite absent. Metaventrite flat to slightly convex, or moderately to strongly convex. Transverse groove of metaventrite absent, or present. Anterior edge of metaventrite without transverse carina between mesocoxal cavities. Exposed portion of metepisternum short and broad, or moderately elongate. Metacoxae contiguous or narrowly separated; not extending laterally to meet elytra or sides of body, or extending laterally to meet elytra or sides of body; completely separated from metaventrite by suture. Metacoxal plates well developed, more or less uniform, or well developed mesally, weak laterally, or weakly developed; not concealing most of basal abdominal ventrite. Metacoxae not greatly enlarged; horizontally oriented, or obliquely oriented. Lateral arms of metendosternite short or absent, or moderately to very long. Metendosternal laminae absent. Ventrolateral processes of metendosternite absent or weakly developed, or strongly developed. Anterior process of metendosternite moderately long, or short or absent. Anterior tendons of metendosternite moderately or very close together. Apical portion of metendosternite not or only slightly emarginate.

Hind wing. Hind wing well developed; with normal transverse folds. Radial cell of hind wing well developed; elongate. Inner posterior angle formed at base of radial cell right or obtuse, or acute. Radial cell not forming equilateral triangle. Ratio of length of apical area to total wing length less than 0.2, or 0.20–0.35. Medial bar of hind wing not crossed by fold. Free veins in medial area of hind wing 5 or 6, or 4, or 3 or fewer. Oblongum cell of hind wing absent. Medial fleck of hind wing absent; absent or not partly bisected by a vein. Wedge cell of hind wing well developed, or reduced, or absent. Anal lobe of hind wing absent. Posterior edge of hind wing without fringe of long hairs.

Legs. Femoral attachment of mid trochanter transverse or slightly oblique, or strongly oblique with base of femur separate from coxa. Mesotrochanter not reduced or concealed from below. Metafemur not much wider than mesofemur. Mesotibia not strongly widened. Outer edge of mesotibia simple, crenulate or denticulate, or with distinct teeth or long spines. Outer subapical edge of mesotibia without antenna cleaner. Preapical surfaces of mesotibia without ridges or combs. Outer apical angle of mesotibia simple or slightly produced, without lobe, teeth or spines. Mesotibial spurs glabrous or absent, or pubescent. Mesotarsus with 5 distinct tarsomeres (pentamerous), or with 4 distinct tarsomeres and reduced penultimate one (pseudotetramerous). Tarsomeres on hind leg at least as many as on mid leg. Tarsomeres on fore leg at least as many as on mid leg. Mesotarsomere 1 well developed and visible. Preapical mesotarsomeres together longer than apical one. Penultimate mesotarsomere not distinctly shorter than antepenultimate, or distinctly shorter than antepenultimate. Ventral mesotarsal lobes absent, or on penultimate tarsomere only, or on antepenultimate tarsomere only, or on more than one tarsomere. Mesotarsal claws paired; subequal in length and similar in form and angle of inclination; simple, or toothed or bifid, or serrate, denticulate or pectinate. Appendage on each tarsal claw absent. Mesotarsal claws without setae near base. Mesotarsal empodium absent or with 2 or fewer setae. Inner subapical edge of protibia without antenna cleaner. Hind legs without swimming hairs. Preapical surfaces of metatibia without ridges or combs.

Abdomen. Number of abdominal ventrites 5, or 6. Number of basal ventrites connate three. Abdominal sternite 2 apparently absent. First ventrite not completely divided by metacoxae. Suture between ventrites 1 and 2 distinct. Suture between ventrites 2 and 3 distinct. Ventrite 4 articulated with or connate with both 3 and 5. Postcoxal lines on ventrite 1 absent. Ventrite 1 not much longer than 2. Abdominal process acute or narrowly rounded. Ventrite 5 in female without circular depression. Posterior edge of ventrite 5 not crenulate. Last visible tergite and-or sternite (7 or 8) not forming terminal spine. Subapical abdominal luminous organ absent. Ventrites without setose patches or foveae. Functional spiracles on abdominal segment 8 absent. Anterior edge of sternite 8 in male without median strut, or with median strut. Anterior edge of sternite 9 in male without median strut, or with median strut (spiculum gastrale). Tergite 9 in male truncate, or slightly to moderately emarginate, or deeply emarginate, or almost completely divided into two parts. Tergite 10 in male well developed and free, or partly fused to tergite 9.

Aedeagus trilobate; symmetrical. Anterior edge of tegmen or phallobase without struts. Parameres individually articulated to phallobase or base of penis; not outwardly hooked. Penis without dorsal and ventral lobes. Anterior edge of penis without struts, or with paired struts.

Illustrations. • Telon. Telon cucullatus Champion. Locality: Central America. Reference: Champion 1897. • Araeopidius. Araeopidius monachus (LeConte). Locality: British Columbia. Photo: K. Smith. Copyright CSIRO. • Drupeus. Drupeus sp. Locality: China. Photo D. McClenaghan. Copyright CSIRO. • Octoglossa. Octoglossa sp. Locality: Panama. Photo: K. Smith. Copyright CSIRO. • Chaetodactyla. Chaetodactyla lyciformis Champion. Locality: Central America. Reference: Champion 1897.


The interactive key provides access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, and summaries of attributes within groups of taxa.

Cite this publication as: ‘Lawrence, J.F., Hastings, A.M., Dallwitz, M.J., Paine, T.A., and Zurcher, E.J. 2000 onwards. Elateriformia (Coleoptera): descriptions, illustrations, identification, and information retrieval for families and subfamilies. Version: 9th October 2005. http://delta-intkey.com’.

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