Onichodon orchesides Newman, 1838

Otto, Robert L., 2013, Eucnemid Larvae of the Nearctic Region. Part III: Mature Larval Descriptions for Three Species ofOnichodonNewman, 1838 (Coleoptera: Eucnemidae: Macraulacinae: Macraulacini), with Notes on Their Biology, The Coleopterists Bulletin 67 (2), pp. 97-106 : 97-106

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https://doi.org/ 10.1649/0010-065X-67.2.97

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Onichodon orchesides Newman, 1838


Onichodon orchesides Newman, 1838 fifth instar ( Figs. 6–10 View Fig View Figs )

Diagnosis. The shape of the dorsal prothoracic scleromes, along with a slightly elongate, narrowly bifurcate first lateral projection of the head capsule, sclerotized caudal end of the ninth abdominal segment, and circular ring of asperities around the anal region should distinguish this species from its close relatives, O. canadensis and O. rugicollis .

Specimens Examined. Six mature larvae collected at USA: Wisconsin: Richland County, 3.2 km W. Lone Rock, 9.x.1994, Daniel K. Young, in white rot oak log .

Description. Length 34.0–39.0 mm, width 3.0–4.0 mm. Orthosomatic. Body ( Fig. 6 View Fig ): Subcylindrical, sides parallel, yellow with head, prothoracic sclerome patches, and caudal end of 9 th abdominal segment dark brown. Setae reduced or absent. Pair of small legs reduced to dome-like structures present near posterolateral areas of each thoracic segment. Dorsal and ventral microtrichial patches slightly darker than their surrounding areas. Head ( Fig. 7 View Figs ): Strongly flattened, prognathous, and inserted into prothorax. Dorsal and ventral cephalic discs oblonged, subtrapezoidal and simple. Anterior portion of the head capsule heavily sclerotized. Posterior areas of the head capsule unsclerotized. Each lateral side of head capsule with 6 projections. First lateral projections slightly elongate, narrowly bifurcate, directed anterolaterally. Second through 6 th lateral projections directed anterolaterally. Second and 3 rd lateral projections narrowly spaced apart. Antennae minute, arising between 5 th and 6 th lateral projections. Scape not visible. Pedicel elongate. Sensorum and flagellum subequal in length. Sensory papillae indistinct. Mandibles minute, resting in the mesal acumination of the head capsule between 6 th lateral projections. Each mandible heavily sclerotized, distinct, oval, longer than wide with 2 outwardly projecting teeth. Maxillary palpi extremely small, 3-segmented. Ligula, mala, lacinia, and galea not visible. Hypostomal rods absent. Prothorax ( Figs. 8, 9 View Figs ): Subequal to subsequent 2 thoracic segments. Tergum with pair of square scleromes. Arrowhead microtrichial patch between scleromes. Tergum and sternum without areoles. Sternum with triangular scleromes and smaller, more rounded microtrichial patch. Meso- and metathorax: Each tergum and sternum with kidney-shaped microtrichial patch of short triangular extension coming from mediocaudal region directed towards the posterior end. Anterior ¾ of each tergum with longitudinal plicae and carinae, surrounding each microtrichial patch and extending towards posterior end. Pair of elongate oval areoles present near posterior end of the metathoracic segment. Mesothorax without spiracles. Metathoracic sternum with oblong areole near posterior end. Abdomen: Segments I-IX subequal in length and width. Terga and sterna I-VIII with microtrichial patches that successively change from oval on segment I to subcircular on segment VIII. Terga and sterna I-VIII with very oblong, oval areole present near posterior end. Tergum IX without microtrichial patch, sparsely punctate near the caudal end; sternum ( Fig. 10 View Figs ) heavily sclerotized in caudal half with prominent, circular ring of asperities around anal region. Urogomphi absent on segment IX. Spiracles annular-biforous.

Distribution. Onichodon orchesides is known from CANADA: New Brunswick, Ontario, Québec; USA: Arkansas, Delaware, Illinois, Indiana, Iowa, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Hampshire, New Jersey, New York, North Carolina, North

9) Head and thoracic region, ventral view; 10) Abdominal segments VIII-IX, ventral view.

Dakota, Oklahoma, Pennsylvania, Vermont, West Virginia, and Wisconsin ( Muona 2000; Webster et al. 2012). All specimens used in this study came from Wisconsin.

Biology. Onichodon orchesides is a widespread and somewhat commonly collected species found largely in the eastern United States and Canada. In Wisconsin, O. orchesides was found in a variety of forest systems. Adults and larvae were found in northern dry-mesic forest, northern hardwood swamp, northern mesic forest, northern wet-mesic forest, oak barrens, oak openings, southern dry forest, and southern mesic forest systems. Larvae were collected in rotten red oak log in southwestern Wisconsin. Based on label information, collectors in Wisconsin have found the species in Lindgren funnel traps, unbaited Townes Malaise trap, flight intercept traps, Malaise traps, purple prism traps, at blacklight, and 11 adults were reared from larvae in cottonwood ( Populus deltoides Bartram ex. Marshall) in southern Wisconsin.

Kirk (1922) found larvae inside decaying willow ( Salix sp. ; Salicaceae ) and river birch ( Betula nigra L.) logs in swamps. Muona (1993) wrote that the species was found on silver maple. Muona (1996) also wrote that O. orchesides uses beech as a host. Webster et al. (2012) found six adults during a trapping survey in New Brunswick. These beetles were captured in Lindgren funnel traps placed in mature hardwood forests with American beech, old red oak forest, old silver maple forest, and old red pine forests during the months of July and August.