The life history of Caurinus dectes Russell, with a description of the immature stages (Mecoptera: Boreidae)

Abstract

The egg, larva, and pupa of Caurinus dectes are described and illustrated. Eggs are ellipsoidal, coated with black cement, and are attached to bryophytes. The larva is orthosomatic, with much-reduced thoracic legs, and further differs from other larval Boreidae in: amphipneustic spiracles, number of stemmata (7), placoid sensilla present in membrane of first antennal segment, and egg burster on frons in first instar. Three larval instars are recognized from analysis of head measurements and partial rearing. Larvae feed in stemmines or galleries in leafy liverworts (Jungermanniales). Pupation occurs in a silk-lined cell or cocoon, otherwise unknown in the Mecoptera; the pupa is exarate, with decticous mandibles. The seasonal occurrence of egg eclosion (February-March), pupation (July-August), and principal adult activity (October-April) is typical for the Boreidae, but only C. dectes is univoltine in this family. Successive annual generations appear to overlap through extended egg diapause and adult perenniation.

Embryonic development of the scorpionfly Panorpa emarginata Cheng with special reference to external morphology (Mecoptera: Panorpidae)

“…Yie (1951) considered that the abdomen consists of 10 segments. The last part of the abdomen, the anal fork, was regarded as the eleventh segment by Byers (1963) in the scorpionfly Panorpa nuptialis and by Russell (1982) in the snow scorpionfly Caurinus dectes, while the fourbranched retractile anal fork was considered to belong to the tenth (and the last) abdominal segment (Miyake, 1912). In his comprehensive investigation on the embryological development of the Mecoptera, Suzuki (1990) also failed to recognize the presence of the eleventh abdominal segment.…”

Description of Caurinus tlagu, new species, from Prince of Wales Island, Alaska (Mecoptera, Boreidae, Caurininae)

“…This does raise questions about the feeding and breeding ecology of Caurinus tlagu . Russell (1979b, 1982) documented Caurinus dectes as a specialist on epiphytic and terrestrial leafy liverworts (Jungermanniales). We lack adequate data on the bryophyte communities of the lowland forested sites to assess whether Caurinus tlagu shows the same bryophyte associations as Caurinus dectes .…”

“…Russell (1982) describes adult Caurinus dectes as primarily active during the winter (October – April), but reappearing in unseasonably wet, cool weather during the summer. This contrasts with our findings of summer presence of adult Caurinus tlagu .…”

“…Russell (1979a, b, 1982) described the monotypic subfamily Caurininae, genus and species Caurinus dectes , known only from Oregon and Washington, and later described by Beutel et al (2008) as “arguably one of the most bizarre and cryptic species of Mecoptera and endopterygote insects.” Indeed, members of the genus do not key to any order in most keys to insect orders because they lack a produced rostrum, typical of the order Mecoptera, and lack the diagnostic traits that would place them within any insect order containing flightless adults with rudimentary or vestigial wings. However, they do share with members of the family Boreidae a very distinctive wing morphology and sexual dimorphism in which the adult females are nearly wingless while the males bear shortened scissor-like wings, useless for flight, that bear spines for grasping females during mating.…”

“…The placement of Caurinus within the Mecopteran family Boreidae as the sister taxon to the Boreinae ( Boreus 26 spp., Hesperoboreus 2 spp. [Penny 2013]), is apparently well established based on morphological study (Russell 1979a, b, Beutel et al 2008, Friedrich et al 2013) and molecular phylogenetics (Whiting 2002). However, despite recent efforts, the genus remains enigmatic due to its preponderance of plesiomorphic and autapomorphic traits (Beutel et al 2008).…”