- aesthetasc
- Thin-walled chemosensory seta usually found on antennular flagellum.
- antennules
- Antennae 1 or first antennae; anteriormost paired appendages of head (= antennula).
- antennae
- Antennae 2 or second antennae; second paired appendages of head.
- appendix masculina
- Copulatory stylet arising from medial margin of male pleopod 2 endopod, used for transfer of spermatophores in at least some species. (Pl. appendices masulinae)
- biramous
- Composed of two rami or branches.
- carina
- A keel, or acute ridge.
- cephalon
- Head; strictly speaking the cephalon of an isopod is a cephalothorax, as it is always fused with the first thoracomere (and also with the second thoracomere in the Gnathiidea).
- chelate
- Having a chela; the propodus and dactylus forming a pincerlike structure wherein the latter articulates submedially on the former to produce a "moveable and fixed finger" arrangement. (True chelae are extremely rare in isopods.)
- coupling setae
- When present, coupling setae (or hooks) occur on the maxillipedal endites and pleopodal peduncles, and serve to lock the opposing appendages together, allowing them to function as a single unit.
- coxa
- Basal article of an appendage.
- coxal plates
- Coxae of the pereopods laterally expanded into flattened lamellar structures extending freely (as "plates") to overhang the coxa-basis hinge of the leg.
- clypeus
- In most (but not all) isopods the labrum consists of two pieces; the anteriormost (proximal) piece is referred to as the clypeus, the posteriormost (distal) piece as the labrum proper.
- distal
- Situated away from the base or point of origin or attachment.
- endite
- A lobe on the inner (medial) margin of the protopod of an arthropod limb; enlarged anteriorly directed lobe of the basis of an isopod maxilliped.
- endopod
- Inner (medial) ramus of an appendage.
- exopod
- Outer (lateral) ramus of an appendage.
- flagellum
- Narrow distal part of antenna or antennule, usually multiarticulate, occasionally reduced to one or a few articles, without intrinsic musculature.
- frontal margin
- Separates the upper surface of the cephalon from the frontal lamina; anterior margin of cephalon.
- frontal lamina
- A sternal plate arising between the bases of the antennae and probably homologous to the epistome of other arthropods.
- frontal process
- The lower region of the epistomal plate or sclerite, which in some Valvifera projects outward to become visible in the dorsal aspect as a protuberance lying above the frontal lamina.
- gnathopod
- A loosely used term usually refering to chelate or subchelate pereopods associated with the head region and used for food handling. This term is rarely used for isopods.
- incisor process
- Grasping, piercing or slicing structure arising apically on body of mandible.
- labium
- The posterior border of the buccal field; the "lower lip" (see paragnath).
- labrum
- Flaplike structure posterior to the frontal lamina or clypeus, usually free but occasionally fused to head; the "upper lip" (see clypeus).
- lacinia mobilis
- Small, usually toothed, process articulating at base of incisor of left or both mandibles; present in most isopod groups.
- lamina dentata
- Serrate platelike structure on the mandible of anthurideans, presumed to have been formed by the fusion of spines of the spine-row.
- manca
- Young of most peracarids (including isopods), which lack the 7th pereopod at time of release from broodpouch.
- mandible
- Third pair of head appendages; first (anteriormost) pair of mouthparts functioning as jaws and typically sclerotized.
- marsupium
- Structure in which eggs and embryos are retained and brooded by female; the broodpouch. Isopod marsupia are typically formed by overlapping medial plates (oostegites) arising from certain pereonal coxae in females; in a few groups the oostegites have been reduced or lost in lieu of internal brooding.
- maxillules
- Fourth pair of head appendages, functioning as mouthparts, immediately posterior to mandibles (= first maxillae).
- maxillae
- Fifth pair of head appendages, functioning as mouthparts, immediately posterior to maxillules (= second maxillae).
- maxillipeds
- Modified first pair of thoracopods, functioning as mouthparts.
- molar process
- Grinding, or piercing or slicing structure, arising mid-basally on body of mandible; pars molaris.
- oostegite
- Thin ventromedial plates, born on coxae of some pereopods in female peracarids forming the marsupium, or broodpouch.
- palp
- Articulated ramus consisting of one to three articles on the mandible, and up to five articles on the maxilliped. (Palps do not occur on the maxillules or maxillae of isopods.)
- paragnath
- In isopods the labium is usually produced and cleft into a large bilobed structure, and hence more commonly referred to as the paragnath (= hypostome, metastome, hypopharynx).
- peduncle
- Enlarged proximal, or basalmost region of an isopod antennule, antenna, pleopod, or uropod; contains intrinsic musculature.
- penes
- Paired (occasionally fused) submedian processes from vas deferens on sternum of male pereonite VII or pleonite 1. (Sing. penis)
- pereonite
- A segment of the pereon (= pereomere).
- pereopods
- The paired legs of each pereonite.
- pleon
- Abdomen.
- pleonite
- A segment of the pleon (= pleomere).
- pleopods
- The biramous, paired, lamellar appendages of each pleonite.
- pleotelson
- In all isopods the sixth pleonite is fused to the telson to form a pleotelson. In anthurideans the line of fusion is often visible as a deep dorsal groove or fold.
- praniza
- Juvenile, immature stage of gnathiideans.
- prehensile
- Appendages (usually pereopods) adapted for holding or clinging, the dactyl is as long or longer than the propodus, strongly developed and recurved.
- protandrous
- In sequential hermaphroditic forms, becoming a functional male (producing spermatozoa) before becoming a functional female (producing eggs).
- protogynous
- In sequential hermaphroditic forms, becoming a functional female (producing eggs) before becoming a functional male (producing spermatozoa).
- proximal
- Situated near the base or point of attachment.
- pylopods
- Second pair of maxillipeds in gnathiids (appendages of the second thoracomere).
- rostrum
- Anteromedial projection of frontal margin of cephalon.
- scale
- A small articulate piece occurring on the antennules or antennae in some crustaceans, thought to be a remnant of the second ramus (presumably the exopod). Scales rarely occur in isopods.
- spine row
- Spinose lobe on the mandible, between the molar and incisor processes. The homology of these spines (or setae?) is not well understood.
- statocyst
- Small saclike sensory organ, usually containing a granule(s), used to indicate to the animal its orientation; present singly or paired on the pleotelson of some anthurideans.
- subchelate
- Having a subchela; forming a pincerlike structure by the dactylus folding back on the propodus.
- tergite
- Dorsal sclerite of exoskeleton on arthropods.
- uropods
- The paired biramous appendages of the isopod pleotelson, representing the appendages of the fused sixth pleonite.
Glossary of Isopoda Technical Terms
Richard BruscaAbout This Page
Richard Brusca
Arizona-Sonora Desert Museum, Tucson, Arizona, USA
Correspondence regarding this page should be directed to Richard Brusca at
Page copyright © 2001 Richard Brusca
Page: Tree of Life
Glossary of Isopoda Technical Terms
Authored by
Richard Brusca.
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