Chthamalus fissus Darwin 1854
Creators: name: Pitombo, Fábio Bettini
name: Burton, Ron
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Sessilia
Chthamalidae
Chthamalus
Chthamalus fissus

description: Key to the species of the Chthamalus fissus group of species   
1.- Articular ridge of scutum short, limited to tergal border; lateral depressor muscle pit smooth. Cirrus I without bidenticulate setae. Cirrus II with bidenticulate setae with basal guards on last 2 articles of anterior ramus..................................................................................................................................................... 2  
1’- Articular ridge of scutum wide, developed, sometimes projected beyond tergal border; lateral depressor muscle pit smooth or divided by septa/ridges. Cirrus I with bidenticulate setae with or without basal guards. Cirrus II with bidenticulate setae with basal guards from last 2 to last 5 articles of anterior ramus..................................................................................................................................................................... 4  
 2- Scutum inner face with growth lines on less than 15% its width. Tergum triangular without noticeable spur; outer face without longitudinal ridge close to scutal border .................................................... C. fissus   
2’- Scutum inner face with growth lines on more than 15% its width. Tergum triangular with noticeable spur; outer face with longitudinal furrow close to scutal border in one or both plates (better seen with cleaned plate)............................................................................................................................................................ 3  
 3- Shell brown to white, narrow, deeply folded up to apex. Tergum with well marked longitudinal furrow on both plates; parietes usually white .......................................................................................... C. panamensis   
 3’- Shell brown, smooth, folding limited to lower half. Tergum with weak longitudinal furrow frequently only on one plate; parietes usually brown in uneroded specimens. ................................................. C. hedgecocki   
4- Scutum inner face with growth lines on more than 15% its width.............................................................. 5  
4’- Scutum inner face with growth lines on less than 15% its width................................................................ 6  
 5- Opercular plates strongly asymmetric. Cirrus II with bidenticulate setae with basal guards on last 4 or 5 articles of anterior ramus ......................................................................................................... C. anisopoma   
 5’ - Opercular plates weak asymmetric. Cirrus II with bidenticulate setae with basal guards on last 2 articles, sometimes down to last 3 articles of anterior ramus ........................................................ C. southwardorum   
 6- Scutum lateral depressor muscle pit smooth. Cirrus II with bidenticulate setae with basal guards on last 4 or 5 articles of anterior ramus ........................................................................................................ C. fragilis   
 6’- Scutum lateral depressor muscle pit divided by septa/ridges, sometimes not. Cirrus II with bidenticulate setae with basal guards on last 3 or 4 articles of anterior ramus ................................................... C. proteus
description: Published as part of Pitombo, Fábio Bettini & Burton, Ron, 2007, Systematics and biogeography of Tropical Eastern Pacific Chthamalus with descriptions of two new species (Cirripedia, Thoracica), pp. 1-30 in Zootaxa 1574 (1) on pages 17-18, DOI: 10.11646/zootaxa.1574.1.1, http://zenodo.org/record/5096761