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