antenna

() [Baba, 2005].

^{Antennal peduncle consisting of 5 articles, based on Uroptychus. [Baba, 2005]}

Mobile sensory appendages arising below the eyes at the front of the head. There are two pairs of these appendages, the first and second antennae. The first antennae are uniramous and may have two or three flagellae each. The second antennae are biramous, one branch being similar in gross form to the first antenna, the other being flattened and scale-like (referred to as a scale) [Mauchline, 1984].

More lateral of the two paired, usually flagellate appendages projecting distally from the anterior end of the cephalothorax (Fig. 1). (Pl. antennae) [Perez Farfante and Kensley, 1997].

One of pair of anterior appendages of head region placed morphologically next behind antennule, uniramous in some crustaceans but biramous in all nauplii and in adults of most classes; may be extremely long and composed of multitudinous small segments or reduced to mere rudiment or lacking. (Syn. second antenna) [Moore and McCormick, 1969].

One of pair of appendages of second cephalic somite. (Syn. 2^nd antenna) [McLaughlin, 1980].

Second cephalic appendage, usually with peduncle of five articles and multiarticulate flagellum (sometimes antenna 2); plural sometimes used to refer to both antennules and antennae. (Pl. antennae) [Poore, 2004].

Second pair of cephalic appendages (antenna 2) [Holdich and Jones, 1983].

The appendages of the second and third head segments are the first and second pairs of antennae respectively. The first antennae are secondarily biramous (Fig. 3) Both pairs of antennae are sensory [Warner, 1977].

The more lateral of the the two paired flagellate appendages projecting anteriorly from anterior end of the body. (Pl. antennae) [Butler, T.H.].

The more lateral of the two paired flagellate appendages projecting anteriorly from the anterior end of the body. (Pl. antennae) [Chace and Hobbs, 1969].

The second pair of appendages situated between the antennules and the orbits, sometimes referred to as second antennae [Ingle, 1983].

The second, paired, cephalic appendage. It consists of four short, robust, proximal segments, two long, intermediate segments, and a long series of tapering annuli, called the flagellum. The third basal segment bears a smaller, lateral appendage called the antennular scale that is homologous to the exopod in other Crustacea. (Syn. second antenna) [Wilson, 1989].

Whiplike, generally long sensory organ arising from anterior region of cephalothorax (see Figs. 13, 14) [Hobbs and Jass, 1988].

(Order Cladocera):

Second and much larger pair of antennae; located laterally near posterior margin of head. Biramous, consisting of relatively large basal part (peduncle) bearing twoto four-segmented dorsal and ventral branches (rami). Serves as principle locomotory organ and moved by relatively large muscles (antennal muscles). (biramous and flattened, simple and cylindrical, branched, not branched). (Syn. second antenna) [Stachowitsch, 1992].

(Order Notostraca):

Second and smaller pair of antennae; uniramous, extending from each side of labrum on underside of head. (very small, vestigial, absent). (Syn. second antenna) [Stachowitsch, 1992].

(Order Diplostraca):

Second and much larger pair of antennae on head; biramous, consisting of long, terminally annulate basal part (protopod, with basal lobe) and pair of segmented branches (flagella, rami). (Syn. second antenna) [Stachowitsch, 1992].

(Order Anostraca):

Second and larger of two pairs of antennae; uniramous, projecting ventrally from head. In female, typically unsegmented and reduced. In male, forms clasper generally consisting of exapanded basal segment (with antennal appendage) and more slender distal segment. (fused at base, not fused at base; basal segment: with/without hand; with/without fingerlike process on median surface near midlength; with prominent, dorsally directed, peg-like process on median surface just below mid-length; with row of spines along median margin; with spinous pad, median protuberance, and many small distal spines; distal segment: laminate, not laminate, with/without calcar) (see also clypeus, hand). (Syn. second antenna) [Stachowitsch, 1992].

(Class Cephalocarida):

Second pair of antennae. Biramous, consisting of twosegmented protopod, relatively short, two-segmented endopod, and longer, multi-segmented exopod. Serves in locomotion and feeding. (Syn. second antenna) [Stachowitsch, 1992].

(Order Cumacea):

Second pair of antennae; uiramous. If fully developed, consisting of proximal five-segmented peduncle and distal flagellum. (Syn. second antenna) [Stachowitsch, 1992].

(Order Tanaidacea):

Second, relatively small pair of antennae. (Syn. second antenna) [Stachowitsch, 1992].

(Order Decapoda):

Second and typically larger pair of antennae. Originates from second (antennal) somite of head. Biramous, consisting of basal peduncle (typically composed of protopod, endopod, and scaphocerite) and distal flagellum. Bears pore of antennal gland. (elongate, spatulate, squamiform). (Syn. second antenna) [Stachowitsch, 1992].

(Order Amphipoda):

Second pair of antennae. Uniramous, consisting of proximal fivesegmented peduncle and distal flagellum. May bear sensory structures (aesthetascs, calceoli). (short, long; slender, robust; naked, setose, spinose; similar, sexually dimporphic; pediform). (Syn. second antenna) [Stachowitsch, 1992].

(Order Isopoda):

(pl. antennae) [Wetzer et al. 1997].

()

^{Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]}

(Order Isopoda):

Paired appendage of the third cephalon segment; sometimes referred to as antenna 2 [Kensley and Schotte, 1989].

()

^{Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]}

(Order Isopoda):

Second, usually longer appendage of cephalon. Uniramous, consisting of basal peduncle and distal lagellum. (pediform). See: accessory flagellum, antennal scale [Stachowitsch, 1992].

(Order Mysida):

Second pair of antennae. Biramous, consisting of peduncle bearing scale-like outer branch (antennal scale, squama, exopod) and elongate inner branch (flagellum). (Syn. second antenna) [Stachowitsch, 1992].

(Order Stomatopoda):

Second and smaller pair of antennae; originating from second somite of head (cephalon). Biramous, consisting of basal, two-segmented peduncle, two-segmented exopod (distal segment = antennal scale), and three-segmented endopod (with distal flagellum). (See also antennule). (Syn. second antenna) [Stachowitsch, 1992].

(Order Leptostraca):

Second pair of antennae. Uniramous, relatively long, and consisting of three- or four-segmented peduncle and variously shaped endopod (flagellum). (peduncle: three-/four-segmented; flagellum: long with many small joints, small with few large joints). (Syn. second antenna) [Stachowitsch, 1992].

(Subclass Branchiura):

Second pair of appendages on underside of head. Relatively short, uniramous, and consisting of four to six segments. Armed basally with large spines/hooks, terminally with smaller spines. Serves in attachment to host. (Syn. second antenna) [Stachowitsch, 1992].

(Subclass Cirripedia):

Biramous second pair of antennae. Present, with the exception of certain ascothoracicans, only in early larval stages (nauplius). (Syn. second antenna) [Stachowitsch, 1992].

(Subclass Copepoda):

Second and typically shorter pair of antennae on underside of head. Highly setose and serving in suspension feeding or, in certain parasitic copepods, with terminal claw and serving in attachment to host. If uniramous, outer branch (exopod) is missing. The term second antenna is often preferentially applied. (biramous, uniramous; prehensile). (Syn. second antenna) [Stachowitsch, 1992].

(Subclass Copepoda):

The limb of the cephalon posterior to antenna 1; on most naupliar stages, it bears a distinct protopodal masticatory arthrite which is not present on copepodid stages or on non-feeding naupliar stages, especially those of species with lecithotrophic embryos. (Syn. antenna 1) [Ferrari and Dahms, in press].

(Subclass Copepoda):

The second cephalic appendage [Boxshall and Halsey, 2004].

(Subclass Mystacocarida):

Second and smaller pair of antennae. Biramous, consisting of basal protopod bearing nine-segmented exopod and four-segmented endopod. Serves in locomotion and feeding. (Syn. second antenna) [Stachowitsch, 1992].

(Class Ostracoda):

Second pair of antennae on head. Basically biramous, consisting of basal protopod and distal endopod and exopod (the latter often being reduced). Serves, along with antennules, as chief locomotory appendage. Carapace margin may be indented (rostral notch) for antenna. (biramous, uniramous). (Syn. second antenna) [Stachowitsch, 1992].

(Class Remipedia):

Second and smaller, more paddle-shaped pair of antennae on underside of head (cephalon); biramous and consisting of protopod (with two articles) bearing scalelike exopod and three-segment endopod. Endopod articles arc around anterior aspect of exopod. Setae on antenna are plumose. (Syn. second antenna) [Stachowitsch, 1992].

(Superorder Syncarida):

Second pair of antennae. Consists of basal peduncle and either single flagellum (stygocaridacean), single or paired (flagellum and small exopod) branches (bathynellacean), or flagellum and scaphocerite (anaspidacean). (uniramous, biramous). (Syn. second antenna) [Stachowitsch, 1992].

(Order Thermosbaenacea):

Second, relatively small pair of antennae. Uniramous, consisting of peduncle and flagellum. (Syn. second antenna) [Stachowitsch, 1992].

(Order Euphausiacea):

Second pair of antennae. Biramous, consisting of proximal single-segmented peduncle, scale-shaped outer branch (exopod = scaphocerite), and inner branch (endopod) consisting of three larger segments and multiarticulate flagellum. Peduncle bears opening of antennal gland. (Syn. second antenna) [Stachowitsch, 1992].