Skip to main content

Advertisement

Table 1 Morphological characteristics of the different stages of the life cycle of Cymothoa frontalis

From: Cymothoa frontalis, a cymothoid isopod parasitizing the belonid fish Strongylura strongylura from the Malabar Coast (Kerala, India): redescription, description, prevalence and life cycle

Characteristics Ovigerous female Male Transitional stage Juvenile Manca Pre-manca
Colour Light grey with highly pigmented dorsal surface Creamy white with a pigmented lateral and posterior margin of pereonites Similar to that of ovigerous female in late stage Transparent with scattered chromatophores Clear with scattered chromatophores particularly on uropods and pleotelson Similar to that of manca
Site of infestation On the floor of the buccal cavity, the cephalon facing the opening of the host mouth On the floor of the buccal cavity, on gill arch just behind the female Similar to that of female Usually in pairs, attached on the lower mucous membrane of the beak of the host Found in the brood, then released in to water at inter-moult stage and lead a short free swimming life, and finally the manca either attaches to the body surface of the specific host or may die Seen with in the brood pouch
Size 2.6 times as long as wide. Widest at pereonites 5 to 6 Body 2.67 times as long as wide Body 2.7 times as long as wide Body approximately 3 times as long as wide Body 3.5 times as long as wide Body 4 times as long as wide
Cephalon Partially immersed in poorly developed amphicephalic processes of pereonite 1, as long as wide Cephalon not immersed in pereonite 1 Cephalon partially immersed in poorly developed amphicephalic processes of pereonite 1, as long as wide, anterior margin truncate Anterior margin of cephalon rounded, not immersed in pereonite 1 Cephalon wider than long, 1.6 times as wide as long and golden yellow in colour Cephalon 1.4 times as wider than long and not immersed in pereonite 1
Pereon With 7 pereonites. Coxae not visible in dorsal view With 7 pereonites Coxae not visible in dorsal view With 7 pereonites. Coxae not visible in dorsal view With 7 pereonites. Coxae not visible in dorsal view With 7 pereonites. Coxae not visible in dorsal view With 7 pereonites. Coxae not visible in dorsal view
Pleon With 5 pleonites With 5 pleonites With 5 pleonites With 5 pleonites With 5 pleonites With 5 pleonites
Pleotelson Pleotelson 1.6 times as wide as long, wider than pleonite 5, posterior margin broadly rounded Pleotelson 2 times as wide as long, wider than pleonite 5, posterior margin broadly rounded Pleotelson 1.8 to 2 times as wide as long Pleotelson as long as wide, apical margin rounded with many setae Pleotelson 1.2 times as wide as long and the apical margin with 18 to 20 plumose setae Apical margin without setae, dark pigmentation
Eye Eyes small, not very developed but moderately distinct Eyes small, much prominent than that of female Eyes small and moderately distinct Eyes prominent, ovate and conspicuous in dorsal view Eyes black, prominent, ovate and conspicuous in dorsal view Eyes black, prominent, ovate and conspicuous in dorsal view
Antennule Antennule, stouter than antenna, subequal in length to antenna, composed of 8 articles; articles 1 to 3 slightly wider than others Antennule, stouter than antenna, subequal in length to antenna, 8 articled; first three articles slightly wider than other Similar to that of ovigerous female Antennule 8 articled, extending to anterior margin of pereonite 1; articles 5 to 8 with 3 to 5 spinules and article 8 with few terminal aesthetascs Antennule, 8 articled, extending to anterior margin of pereonite 2; article 5, 7 and 8 with 2 setae and article 6 with one seta. All the articles with 3 to 4 spinules and article 8 with four terminal aesthetascs 8 articled antennules smaller than antennae. Without setae and spinnules
Antenna Antenna 9 articled, decreasing gradually in width, distal margin of articles 6, 7 and 8 with 3 to 6 setae; article 9 with 3 terminal aesthetascs Antenna 9 articled, decreasing gradually in width, distal margin of articles 6, 7 and 8 with 3 to 6 setae; article 9 with 3 to 6 terminal aesthetascs Similar to that of ovigerous female Antenna longer than antennule, 9 articled, extending to anterior margin of pereonite 2; articles 6 to 9 with few spinnules, inner margin of article 3 with 4, article 4 with 5 and terminal of article and 9 with 3 setae; distal margin of article 4 and 5 with 1 plumose setae Antenna longer than antennules, 11 articled, extending to anterior margin of pereonite 4; all the articles with spinnules and article 11 with 4 terminal aesthetascs. Inner margin of article 3 with 1 plumose seta Antenna is larger than antennule and 11 articled. Without setae and spinnules
Mandible Mandible palp 3 segmented, without setae Mandible palp 3 segmented, articles 2 and 3 with several setae on distolateral margin Similar to that of male Mandible palp article 2 with 4 to 6 marginal seta; article 3 with 5 to 8 marginal setae and 1 apical recurved seta Mandible palp article 2 with 1 seta arising from the distal margin; article 3 with 3 marginal setae and 1 apical recurved seta Not well developed. Palp without setae
Maxilla With 2 spines on median lobe and 1 spine on lateral lobe Bi-lobed, with 2 spines on median and lateral lobes Similar to that of male Similar to male stage Similar to male stage Not well developed
Maxillule With 4 apical spines, slightly recurved With 4 apical spines, slightly recurved With 4 apical spines, slightly recurved Similar to male stage Similar to male Not well developed
Maxilliped Maxilliped with oostegial lobes with many plumose setae and a palp with 3 small apical and 2 lateral recurved spines on article 3 Without oostegial lobes and 5 apical recurved spines on article 3 of palp Similar to that of male Similar to male stage Similar to that of male Not well developed
Pereopods Gradually increased in size from 1 to 7, without spines; broad basis increasing in width progressively from p1-p7 Pereopods 1 to 7 gradually increased in size, without spines; basis increasing in width progressively Similar to that of ovigerous female Pereopod 1 without spines, pereopods 2 to 5 with 1 to 2 spines on posterior margin of propodus; pereopod 3 and 5 with 1 spine on the posterior margin of merus and the vestigial pereopod 7 with 3 to 4 spines on carpus and 4 to 6 spines on propodus. Pereopods 1 to 3, dactylus with vestigial teeth; dactylus of pereopods 2 and 3, about 2 times longer than propodus, pereopod 7 with short and blunt dactylus 6 pereopods; pereopod 1, with 1 spine on merus and carpus. Pereopod 2 with 1 spine on posterior margin of merus; pereopod 3 with 1 spine on the posterior margin of merus and propodus. One spine on the posterior margin of propodus of pereopod 4; pereopod 5 and 6 with 1 spine on carpus and 2 to 3 spines on the posterior margin of propodus. Dactyls of pereopods 1 to 3 toothed, 4 to 6 not toothed Only 6 pereopods. Pereopod 7 is missing. Without spines
Penes Absent Penes visibles on sternite 7 Rudimentary penes visible on sternite 7 Poorly developed penes on sternite 7 Absent Absent
Brood pouch Brood pouch made up of 4 pairs of overlapping oostegites arising from the bases of pereopods 2, 3, 4 and 6 - - - -  
Pleopods Pleopods not distinctly visible in dorsal view. Pleopod 2 without appendix masculine. Endopods of pleopods 4 and 5 moderately or strongly folded, respectively Pleopods not distinctly visible in dorsal view. Pleopod 2 with appendix masculine. Endopodite of pleopods 4 and 5 moderately or strongly folded Pleopod 2 with appendix masculina like that of male The lateral margin of exopodite of all pleopods with few setae and the median margin of protopod with 4/5 retinaculae. Pleopod 2 with thick and vestigial appendix masculina, as long as endopodite. Pleopods 1 and 3 subequal. Endopods of pleopods 4 and 5 moderately folded Pleopods not distinctly visible in dorsal view. Pleopod 1 with 4 to 6 plumose setae on endopodite and 14 to 18 plumose setae on exopodite. Pleopods 2 to 5, apical margin of exopodite with 14 to 18 plumose setae Exopodite without plumose setae. appendix masculine not developed
Uropods Uropod rami short, not reaching the distal margin of pleotelson; rami subequal in length, curved and apically rounded Uropod rami short, not reaching the distal margin of pleotelson; rami subequal in length, curved and apically rounded Pleotelson 1.8 to 2 times as wide as long and uropods similar to those of ovigerous female Pleotelson as long as wide, apical margin rounded with many setae. Uropods extending beyond the distal margin of pleotelson, inner margin of basis with 3 to 4 plumose setae; rami subequal in length but exopodite slightly shortest, curved and apically round; exopodite with 40 to 44, and the endopodite with 60 to 64 setae Pleotelson 1.2 times as wide as long and the apical margin with 18 to 20 plumose setae. Uropod basis extending beyond the distal margin of pleotelson; rami subequal extending strongly beyond the distal margin of pleotelson, apically rounded with 8 to 12 plumose setae. Uropods and pleotelson with many dark chromatophores Uropods extending beyond the pleotelson, rami subequal; dark pigmentation only on the uropods and pleotelson