First instar nymphs of two peltoperlid stoneflies (Insecta, Plecoptera, Peltoperlidae)

Shodo Mtow,Tadaaki Tsutsumi

doi:10.3897/dez.68.65540

Abstract

The first instar nymphs of two peltoperlid stoneflies, i.e.,Microperla brevicaudaKawai, 1958 of Microperlinae andYoraperla uenoi(Kohno, 1946) of Peltoperlinae, were examined and described. Additionally, the phylogeny and groundplan of the first instar nymphs of Peltoperlidae and Plecoptera were considered. The first instar nymphs ofM. brevicaudahave a slender body with a prognathous head of typical shape; they represent a groundplan in Plecoptera. On the other hand, the first instar nymphs ofY. uenoihave a broad, cockroach-like body with an orthognathous and shortened head, the latter being regarded as a potential autapomorphy of Peltoperlinae. Such differences in body shape between the subfamilies are speculated to arise from heterochrony. The three-segmented cerci ofY. uenoiare characteristic to Systellognatha, whereas the four-segmented cerci ofM. brevicaudawere independently acquired within Microperlinae. The structure and distribution pattern of chloride cells in the first instar nymphs of Plecoptera were also discussed. The presence of coniform chloride cells is a potential groundplan of Arctoperlaria. One to two pairs of chloride cells are distributed on the first nine abdominal segments ofM. brevicauda; this represents a groundplan character of Systellognatha. On the other hand, one to four pairs of chloride cells are found on the second to ninth abdominal segments ofY. uenoi; this distribution pattern may be an apomorphic groundplan of Peltoperlinae.

Highlights

Plecoptera, commonly known as stoneflies, are a hemimetabolous, neopteran order containing approximately 3,700 described species with a worldwide distribution on all continents except Antarctica (e.g., Zwick 1973; Fochetti and Tierno de Figueroa 2008; DeWalt and Ower 2019)
In the present study we examined and described, for the first time, the first instar nymphs of two Japanese peltoperlids, i.e., Microperla brevicauda Kawai, 1958 (Kawai 1958) (Fig. 1A) of Microperlinae and Yoraperla uenoi (Kohno, 1946) (Kohno 1946) (Fig. 1B, C) of Peltoperlinae, as two representative species
Coniform chloride cells approximately 10 μm in diameter and 1 μm in height distributed on lateral side of first nine abdominal segments; one pair on first, eighth, and ninth targa; two pairs on second to seventh segments, i.e., one pair on each of second to seventh terga and sterna (Fig. 4A, B, D, E)

Summary

Introduction

Plecoptera, commonly known as stoneflies, are a hemimetabolous, neopteran order containing approximately 3,700 described species with a worldwide distribution on all continents except Antarctica (e.g., Zwick 1973; Fochetti and Tierno de Figueroa 2008; DeWalt and Ower 2019). The suborder Arctoperlaria mainly occurs in the Northern Hemisphere, comprising 12 families within two subgroups, Euholognatha and Systellognatha, which each contain six families, i.e., Scopuridae, Taeniopterygidae, Capniidae, Leuctridae, Nemouridae, and Notonemouridae of Euholognatha, and Pteronarcyidae, Styloperlidae, Peltoperlidae, Perlidae, Chloroperlidae, and Perlodidae of Systellognatha. Peltoperlidae is a systellognathan family present in North America and East Asia; it contains almost 70 described species (DeWalt and Ower 2019) and is comprised of two subfamilies, Microperlinae and Peltoperlinae

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Conclusion