Homology and morphology in Poduromorpha (Hexapoda, Collembola)

Cyrille A D'Haese

doi:10.14411/eje.2003.060

Abstract

The detailed external morphology and general anatomy of the majority of families and subfamilies of Poduromorpha were investigated and compared. This examination was done in relation to the three remaining orders of Collembola: Entomobryomorpha, Symphypleona and Neelipleona. Within Poduromorpha, homologies among the different families and subfamilies are established for general chaetotaxy, and chaeotaxy of head, buccal cone, sensilla of fourth antennal segment, anal valves and tibiotarsus. A consistent and comprehensive nomenclature is proposed for these morphological features unifying those applied in scattered existing studies. Observations on first instars are reported. Comparison of first instars and adult chaetotaxy suggests a possible paedomorphic trend in the evolution of Poduromorpha.

Highlights

The external anatomy of springtails has been investigated for a long time (e.g., Bourlet, 1839; De Geer, 1743; Lubbock, 1873), starting consistently with the work of Börner (e.g., Börner, 1901, 1906, 1913)
Several nomenclatures exist for the same structures according to different groups and usually the homologies have not been clarified
Thirteen species covering the diversity of Poduromorpha were kept in culture for several years in order to study first instars and postembryonic development: Tetrodontophora bielanensis Waga, 1842 (Tetrodontophorinae), Onychiurus ambulans Linné, 1758, Kalaphoruraparadoxa Schäffer, 1900, and Protaphorura armata Tullberg, 1869 (Onychiurinae), Mesaphorura macrocheta Rusek, 1976 (Tullbergiinae), Ceratophysella gibbosa (Bagnall, 1940) and Xenylla tullbergi Börner, 1903 (Hypogastruridae), Podura aquatica Linné, 1758 (Poduridae), Friesea mirabilis (Tullberg, 1871) (Frieseinae), Anurida granaria (Nicolet, 1847) (Pseudachorutinae), Morulina verrucosa Börner, 1903 (Morulinae), Monobella grassei Denis, 1923 and Neanura muscorum Templeton, 1835 (Neanurinae) and an Entomobryomorpha, Folsomia candida Bourlet, 1839 (Isotomidae)

Summary

Introduction

The external anatomy of springtails (class Collembola) has been investigated for a long time (e.g., Bourlet, 1839; De Geer, 1743; Lubbock, 1873), starting consistently with the work of Börner (e.g., Börner, 1901, 1906, 1913). Most studies have focused on single groups of different levels: Subfamily (e.g., Rusek, 1976), genus (e.g., Yosii, 1962) or even a single species (e.g., André, 1988). Almost no attempts have been made to generalize to the other groups, with the exception of a comprehensive work on the labial palps (Fjellberg, 1999). Several nomenclatures exist for the same structures according to different groups and usually the homologies have not been clarified. The main goal of the present work is to establish homologies of the morphological features among the dif ferent groups in Poduromorpha, and to do this in relation to the other orders when possible. It is my intention to provide a comprehensive nomenclature unifying the scattered and incomplete studies available in the literature

Objectives

Methods

Results