Phylum: Arthropoda, Crustacea Grandidierella japonica Class: Multicrustacea, Malacostraca, Eumalacostraca Order: Peracarida, Amphipoda, Senticaudata, A brackish water amphipod Corophiida, Corophiidira Family: Aoroidea, Aoridae Description Antenna 1: The first antenna in males Size: Males up to 22 mm in length, females is more than ½ body length (Chapman and 13 mm long (San Francisco Bay, Chapman Dorman 1975) and is much shorter in fe- and Dorman 1975; Myers 1981). The males. The peduncle is with short accessory illustrated specimen (a male, from Coos flagellum in both sexes (Fig. 1b). The male Bay) is 10 mm in length (Fig. 1). flagellum has 20 articles and is a little longer Color: Black head, mottled grey to grey than peduncle. The female flagellum is equal brown body (Chapman and Dorman 1975) to peduncle and consists of 18 articles with distal parts of limbs white (Stephensen (Stephensen 1938). Male antenna one longer 1938; Chapman 2007). This specimen white than its antenna two (Barnard 1973), however (preserved in ETOH). female antennae are of equal size General Morphology: The body of amphi- (Stephensen 1938) (female not figured). pod crustaceans can be divided into three Antenna 2: Length from ¾ of to longer major regions. The cephalon (head) or than antenna one (Chapman and Dorman cephalothorax includes antennules, anten- 1975) (see antenna 1). Spines present on nae, mandibles, maxillae and maxillipeds peduncle articles 3–5. Male second antenna (collectively the mouthparts). Posterior to stout and flagellum with seven articles the cephalon is the pereon (thorax) with (Stephensen 1938). Female second antenna seven pairs of pereopods attached to pere- length in equal to antenna one and fifth article onites followed by the pleon (abdomen) with of peduncle with four strong spines. Female six pairs of pleopods. The first three sets of flagellum with six articles (not figured). pleopods are generally used for swimming, Mouthparts: Mandible with large mo- while the last three are simpler and surround lar, toothed lacinia mobilis, incisors and long 2 the telson at the animal posterior. The gam- -articled mandibular palp with third article marid family Aoridae is characterized by setose. Maxilliped with 4-articled palp, article separate urosome articles and a biramous four claw-like and article two twice the length third uropod. They also have a short of one and two (Chapman and Dorman 1975). (sometimes absent) rostrum, a long first an- Outer maxilliped plates twice the length of in- tenna and a fleshy telson. Grandidierella ja- ner plates. ponica (see plate 262A, Chapman 2007), Pereon: however, resembles the family Corophiidae Coxae: Reduced (Chapman and Dor- more closely due to the uniramus uropod man 1975), serially arranged and barely con- three (Chapman 2007). tiguous (Barnard 1973) (Fig. 1). Coxal plate Cephalon: one with a medial-ventral tooth (Chapman Rostrum: and Dorman 1975) (just slightly produced in Eyes: A single, oval-shaped, lateral illustrated specimen). eye (Kozloff 1974) that are black and medi- Gnathopod 1: Male gnathopod one is um in size (Stephensen 1938) (Fig. 1). greatly enlarged, “carpochelate” (i.e. not A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hiebert, T.C. 2015. Grandidierella japonica. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. filtering type) (Grandidierella, Barnard 1973; character of G. japonica). It is not fleshy, Chapman 2007). Articles two and five grea- blunt or elongate and the ramus is three times tly enlarged and subequal (Chapman and as long as the peduncle (Barnard 1973) (Fig. Dorman 1975). Article two oval, article three 6). small, article four small and elongate. Ar- Epimera: ticle five with sides parallel and with one en- Telson: Telson uncleft and somewhat swollen larged tooth forming thumb and two smaller (Kozloff 1974), with button-like morphology teeth (Grandidierella, Barnard 1975). and medial groove (Chapman and Dorman Anterior edge of article five with 18–20 1975) (Figs. 1, 2). transverse fine ridges ("stridulating organs’’, Sexual Dimorphism: Male first gnathopod Stephensen 1938) and four spines (Figs. 1, article two is expanded and article five is 1a). Female gnathopod one is small, but large, with parallel sides, teeth and stridula- larger than gnathopod two. Article two is ting organ. All features are lacking in fe- setose and narrow (Stephensen 1938) (Fig. males. Male antenna one is also longer than 5). two and female antennae are equal. Gnathopod 2: Male gnathopod two is Possible Misidentifications simple and much smaller than gnathopod The Aoridae are a family of gammarid one. Article two is twice the length of article amphipods that are tube-building suspension five. Article three is short and dactyl is not feeders found in marine and estuarine habi- chelate (Fig. 1). Female gnathopod two is tats. They are characterized by a short ros- setose, is smaller than gnathopod one and trum, long first antenna, gnathopod one larger with article two about 2/3 length of male ar- than two (in males), a fleshy telson, a long ticle two (Barnard 1973). seventh pereopod (longer than the sixth), dis- Pereopods 3 through 7: Simple, not tinctly separate urosome articles and a bira- prehensile (Barnard 1973) and increasing in mous uropod three. There are four aorid am- length. A character of the Aoridae is a sev- phipod species that are not native to the enth pereopod that is longer than the sixth northeastern Pacific coast (e.g. Aoroides (see plate 269C, Chapman 2007) and the secundus, Microdeutopus gryllotapla), one of seventh pereopod in G. japonica is very long which is G. japonica. At least two aorid gene- (Fig. 1). Female pereopods are with narrow ra that are quite similar to Grandidierella: second articles (Stephensen 1938). Paraoroides, and Aoroides (family Aoridae). Pleon: Paraoroides species have a uniramous third Pleonites: Third pleonite is without uropod (as in G. Japonica), but this ramus is dorsal tooth (Barnard 1975) only as long as the peduncle, not twice or Urosomites: All three urosomites three times as long (Barnard 1973). In short (Fig. 1). The first uropod is biramous Paraoroides, the first gnathopod is not and longer than the second or third. The carpochelate, but only slightly enlarged, the peduncle is with peduncular process and gnathopods are equal in size. The third two anterolateral spines on urosomite article of the first antenna is not elongate, as it (Barnard 1969) (Fig. 3). Second uropod is is in G. japonica. Aoroides species (six local) also biramous (Grandidierella, Barnard have an immensely merochelate male first 1975) and with thin peduncle and long rami gnathopod (Barnard 1975), quite different (Barnard 1975) (Fig. 4). The third uropod is from that of G. japonica. Article four is elon- uniramous, without hooked apical spine or gate, article five is oval, but lacks teeth. The long setae (Barnard 1975) (a defining A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] gnathopod is the filtering type, with long Cheluridae are a wood-boring group that utili- setae. The third uropods in this genus are ze the holes in wood left by boring isopods biramous, not uniramous as in family with a huge dorsal tooth on the third Grandidierella. Aoroides columbiae is a Pa- pleonite. The urosomites form a box-like cific coast species. Other species of structure, and the second uropods are Grandidierella have not been recorded from “flabellate” (i.e. paddle-like). Chelura our area, include a tropical species, G. terebrans is an introduced species found on nottoni, and four freshwater species. the Pacific coast and is the only cheluird Grandidierella japonica closely resembles species found in this region (Chapman 2007). amphipods in the gamily Corophiidae The Ischyroceridae is another closely related (Chapman 2007). family. Members have an unusual thorn-like The gammarid family Corophiidae is rostrum and a rather cylindrical body. The characterized by individuals that build U- telson is broad and short, and it is the second shaped tubes in both soft sediments and on male gnathopod, not the first, in this family hard surfaces, sometimes forming dense ag- which is carpochelate. Ischyroceridae have gregations. Species can be dramatically hooks on the outer ramus of the third uropod sexually dimorphic and, while males may be (like Ampithoidae), but this ramus is short and easier to identify with taxonomically relevant slender, not stout. The inner ramus is also characters including the rostrum and pedun- slender and void of setae. Local genera include Cerapus, Ericthonius, Jassa, cle of second antennae, most females can lschyrocerus, Microjassa and Ruffojassa. be reliably identified to species as well Ericthonius species have a body much like G. (Chapman 2007). Five corophiid genera oc- japonica, cur locally, Americorophium, Corophium, but the first male gnathopod is Crassicorophium, Laticorophium and Mono- normal, and the second is carpochelate (the Grandidierella). corophium. The three common estuarine opposite is true for At least E. rubicornis species in this guide (A. brevis, A. salmonis, two species occur in our area, (=E. hunteri) E. brasiliensis. A. spinicorne) were previously members of and In the genus Corophium (see Shoemaker Podoceridae both gnathopods (especially the 1949), but were transferred to the genus second) are large and subchelate. The first Americorophium in 1997 (Bousfield and urosomite is very long, more than twice the Podocerus, Hoover 1997). length of the second. The genera Dulichia, and Dyopedos occur in our area.