Two Types of Nematocysts in Campanulariidae (Cnidaria, Hydrozoa) Studied by Light and Scanning Electron Microscopy

Abstract

The cnidom was found to consist of several morphologically distinct types of nematocysts in six investigated species of Campanulariidae. Descriptions are provided for b‐rhabdoids (micro‐basic b‐mastigophores) of two sizes, occurring in the polyps of Campunulariu Integra and Clytia hemisphaerica of the johnstoni and gracilis forms, respectively. The smaller nemato‐cyst is the most frequent type and is also abundant in the polyps of Laomedea flexuosa, L. geniculata, L. longissima and L. dichotoma as well as in the medusae of Campanulariidae. Structural details of the two nematocyst types, as revealed by scanning electron microscopy, permit discussion of the classification of the nematocysts. The tube in the two types tapers almost unnoticeably from base to tip. No distinct, proximal enlargement of the tube was discernable in either type, as earlier light microscopical observations have suggested. The proximal armature consists of a right‐handed, triple helix of three separate strands of long, closely‐set, paired spines. In the small nematocyst the distal part of the tube is armed with medium sized spines and the discharged tube forms an obtuse angle to the long axis of the capsule. The discharged, wider tube of the large nematocyst roughly forms a right angle to the long axis of the capsule and is distally armed with minute spines.

Life cycle evolution and systematics of Campanulariid hydrozoans

“…Despite this, these characters form the primary basis for species descriptions in the Campanulariidae. Alternatively, morphological characteristics of the nematocysts, or stinging capsules, can be taxonomically useful in many groups of hydroids, including campanulariids (Ostman, 1979;Gravier-Bonnet, 1987;. But again, some nematocyst characters may be plastic and they are time consuming and require live material to study.…”

“…Ostman (1979;Ostman et al, 1987; has characterized nematocysts of Campanulariid hydroids, and found species-specific differences.…”

Evolução de Staurozoa (Cnidaria): inferências moleculares, morfológicas e de cnidoma

“…Cnidomes have been studied in detail for some hydrozoans, and many reviews corroborate the taxonomic relevance of these observations (e.g., Östman, 1979a, 1979b, 1982Cornelius & Östman, 1987;Gravier-Bonnet, 1987;Marques et al, 2000;Marques, 2001;Peña Cantero et al, 2007), as well for Scyphozoa (viz. Calder, 1971 and Cubozoa (e.g., .…”

“…A compilação de informações acerca do tamanho e distribuição dos nematocistos ultrapassa um século (Bedot, 1896;, mas somente trabalhos mais recentes utilizaram os diferentes tipos de cnidas para propor relações filogenéticas entre as classes de Cnidaria e entre os componentes dessas classes . O cnidoma tem sido estudado detalhadamente em Hydrozoa, e muitos estudos corroboram a importância taxonômica dessas observações (Östman, 1979a, 1979b, 1982Cornelius & Östman, 1987;Gravier-Bonnet, 1987;Marques et al, 2000;Marques, 2001;Peña Cantero et al, 2007), o que também foi demonstrado para Scyphozoa (viz. Calder 1971 e Cubozoa .…”

O gênero Orthopyxis (Cnidaria, Hydrozoa) no Atlântico sul-ocidental: caracterização dos limites inter e intraespecíficos a partir de dados morfológicos e moleculares

“…Muitos estudos demonstraram a importância da análise dos nematocistos e sua morfometria na delimitação de gêneros e espécies em Campanulariidae (Östman, 1979a, 1979bCornelius & Östman, 1987;Lindner & Migotto, 2001), padrão este aqui corroborado. A diferença no comprimento dos nematocistos microbásicos mastigóforos tipo B de Campanularia e Orthopyxis é evidente, com aproximadamente 6µm de variação, constituindo uma importante característica diagnóstica para os gêneros na área de estudo, embora a avaliação de um maior número de espécies de Campanularia seja desejável para corroborar esta hipótese.…”