Ovipositor Internal Microsculpture in the Relic SilverfishTricholepidion gertschi(Insecta: Zygentoma)

Natalia A Matushkina

doi:10.1155/2011/563852

Abstract

The microsculpture on the inside surface of the ovipositor of the relic silverfishTricholepidion gertschi(Wygodzinsky, 1961) (Insecta: Zygentoma) was studied with scanning electronic microscopy for the first time. Both the first and second valvulae ofT. gertschibear rather diverse sculptural elements: (1) microtrichia of various shapes and directed distally, (2) longitudinal ridges, (3) smooth regions, and (4) scattered dome-shaped sensilla. As in several other insects, the distally directed microtrichia most likely facilitate unidirectional movement of the egg during egg laying. Involvement of the ovipositor internal microsculpture also in the uptake of male genital products is tentatively suggested. From a phylogenetic point of view, the presence of internal microsculpture appears an ancestral peculiarity of the insect ovipositor.

Highlights

The “living fossil” Tricholepidion gertschi Wygodzinsky, 1961, is the sole extant member of the silverfish family Lepidotrichidae, which inhabits small isolated regions of coastal redwood forests in southern Oregon and northern California [1]
In order to be used for scanning electron microscopy (SEM), the female postabdomen was washed in water, dissected, and macerated for 10– 12 h at room temperature in 10% KOH
The well-developed ovipositor of insects mostly functions as a penetration organ adapted to egg laying into the oviposition substrate

Summary

Introduction

The “living fossil” Tricholepidion gertschi Wygodzinsky, 1961, is the sole extant member of the silverfish family Lepidotrichidae, which inhabits small isolated regions of coastal redwood forests in southern Oregon and northern California [1]. It has been formally placed in the insect order Zygentoma by the author of the first description. The phylogenetic position of T. gertschi has been subject to debate because of a unique combination of plesiomorphic and apomorphic morphological characters in this species. The relationships of T. gertschi (and, of the whole family Lepidotrichidae) within the basal hexapod lineages constitute one of the most debated issues in hexapod phylogeny. “Tricholepidion is the most promising candidate for a new insect “order” (or, in other words, the only insect species whose ordinal classification remains uncertain)” [12, Page 220]

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