View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of Oregon Scholars' Bank Phylum: Arthropoda, Crustacea Ampithoe lacertosa Class: Malacostraca Order: Amphipoda, Gammaridea Gammarid amphipod Family: Ampithoidae Taxonomy: Known synonyms for A. as body (Barnard 1954). No accessory lacertosa include A. japonica, A. macrurus, A. flagellum is present. scitulus, A. stimpsoni and Dexamine stitulus Antenna 2: Flagellum of the second (Conlan and Bousfield 1982), but only A. antenna is with16 articles (30, Barnard 1954) lacertosa is found in current literature. (Fig. 1). Mouthparts: Lower lip has a gap Description between the sub-lobes of its outer lobes (Fig. Size: Locally, individuals are 12.5–15 mm in 2). length (South Slough of Coos Bay) (Heller Pereon: 1968) and reported to 24 mm in length Coxae: (Chapman 2007). Gnathopod 1: Male gnathopod with Color: Pale green to reddish brown (Straude article five equal to or smaller than article six 1987) with large red eyes and small, densely and palm angle oblique (Fig. 5). Female arranged, diffuse black spots. Individuals gnathopod with article five longer than six in tend to have a similar color to the dominant mature, large females but can be shorter in algae in which they nest (Chapman 2007). younger ones. Female gnathopod palms are General Morphology: The body of oblique (Fig. 6) (Barnard 1965). amphipod crustaceans can be divided into Gnathopod 2: Mature males with three major regions. The cephalon (head) or transverse, sinuous palm (Fig. 4) and females cephalothorax includes antennules, antennae, with oblique palm (Fig. 6). mandibles, maxillae and maxillipeds Pereopods 3 through 7: (collectively the mouthparts). Posterior to Pleon: the cephalon is the pereon (thorax) with Pleonites: seven pairs of pereopods attached to Urosomites: The first uropod is pereonites followed by the pleon (abdomen) without an interramal tooth (Fig. 1b). Uropod with six pairs of pleopods. The first three sets three is with flat, setose inner ramus and two of pleopods are generally used for swimming, curved hooks on the outer ramus (Fig 7). while the last three are simpler and surround Epimera: Two and three with small the telson at the animal posterior. Ampithoid point at posterior corner (Fig. 1a). amphipods are in the suborder gammaridea, Telson: Fleshy, uncleft, rounded with two one of the largest groups of amphipods in small spines laterally (Fig.7). marine and estuarine habitats. They have Sexual Dimorphism: Among amphipods, smooth bodies that are only slightly males generally have larger eyes, antennae compressed (Conlan and Bousfield 1982). and gnathopods (Straude 1987). Sexual Keys to the Ampithoidae generally refer to dimorphism in A. lacertosa is pronounced in male specimens, although sexual dimorphism the gnathopods. may be weaker in this group than others (Chapman 2007). Possible Misidentifications Cephalon: The Ampithoidae are a family of gammarid Rostrum: Lateral lobes present. amphipods characterized by short third Eyes: Eyes oval and red. uropods and rami that possess 1–2 Antenna 1: Flagellum of the first distinctive and stout hooks on the outer antenna, with 42 articles, is twice as long as ramus (Myers and Lowry 2003). They are that of second antenna (Fig. 1) (48–52, usually sexually dimorphic and males are Barnard 1954). Total length is about as long Hiebert, T.C. 2015. Ampithoe lacertosa. 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. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12690 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] easier to identify than females. They are valida is an important estuarine species, herbivorous and live in nests they create occurring in brackish waters on the alga amongst algal blades or within algae stipes. Enteromorpha (E. L. Bousfield, personal There are 10–11 local species in the genus communcation). Ampithoe (A. corallina is currently a questionable species, Chapman 2007), Ecological Information which are generally larger than other Range: Known range includes Japan, amphipod genera (Kozloff 1993). See Alaska, Washington and south to Magdalena Conlan and Bousfield (1982) for detailed Bay, Baja California. account of Ampithoe characters. Local Distribution: Coos Bay sites include Ampithoe simulans is also found in Cape Arago, North Bay, Charleston and marine intertidal habitats of Coos Bay South Slough. (Barnard 1965). This species has an oblique Habitat: Builds tubes or nests in algae (e.g. and concave article on the second Macrocystis) and in eelgrass on mudflats at gnathopod, not a transverse one. This South Slough (Barnard 1975; Straude 1987). article has a large sinus, and a small process Ampithoe lacertosa was also found as a on its inner margin (Barnard 1954). This member of a phytal (drifting seaweeds) species is primarily found on the open coast community collected from northern Japan and lives within Phyllospadix spp. and other (Sano et a. 2003). types of algae (Chapman 2007). Ampithoe Salinity: Collected at salinities of 30. plumulosa, as its name suggests, has a very Temperature: setose second antenna and the first antenna Tidal Level: Intertidal to +0.15 m and is very long. The lower lips gape and are not subtidal to 11 meters deep (Chapman 2007). compressed as they are in A. valida. This Associates: likely introduced species is often found in Abundance: mussel beds (Chapman 2007). Ampithoe pollex does have compressed lower lips and Life-History Information its name comes from its large pointed Reproduction: Most amphipods have process or thumb which meets the dactyl separate sexes with some sex determination (the sixth article of the second gnathopod in correlated with environmental conditions males). Ampithoe aptos has two enlarged (Straude 1987). Females brood embryos in lobes on the apex of the teslon and the fifth an external thoracic brood chamber made up article of pereopod five is less than half as of oostegites (see Fig. 11, Heller 1968) and long as the sixth. On the other hand, irrigate embryos with water flow produced by Ampithoe sectimanus has a telson with small pleopod movement (fifth pleopods in A. knobs and the fifth article of pereopod five is lacertosa). Development within this brood more than half as long as the sixth. chamber is direct and individuals hatch as Ampithoe dalli has plumose setae on the juveniles that resemble small adults, with no anterior edge of the second article of larval stage. Heller (1968) described many gnathopod one (in males). Ampithoe aspects of the biology of A. lacertosa, longimana is North Atlantic species, including the reproductive biology. Although introduced to southern California and A. many amphipod species exhibit an extended ramondi is a cosmopolitan species that is coupling period (e.g. Hyale pugettensis, currently not reported farther north than Point Straude 1987), where males and females are Conception, California. Neither of these physically coupled for several days prior to species are found in current local intertidal copulation, this is not necessary in A. keys (Chapman 2007). lacertosa individuals. Instead, males and The most similar species to A. females inhabit the same nest. Fertilization lacertosa is A. valida, which also has the occurs within the brood chamber and eggs transverse palm in the second male are laid directly into brood pouch from gnathopod, but which has shorter antennae oviducts five hours after fertilization. Eggs are and compressed lower lips. Ampithoe surrounded by a transparent membranous Hiebert, T.C. 2015. Ampithoe lacertosa. 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. sac and broods range in number from 10–155 Predators: The Ampithoe congener, A. (average 64) embryos that are elliptical in longimana, is preyed upon by the pinfish, shape and approximately 450–560 µm in Lagodon rhomboides, and the grass shrimp, diameter. At 8–10˚C, individuals hatch at 22 Palaemonetes vulgaris (Nelson 1979). days post fertilization, but remain in the Behavior: A tube-dweller that builds simple, female brood pouch for another 19 days. but temporary tubes (McDonald and Bingham This timeline increases at warmer 2010). temperatures (e.g. 19 and 10 days at 12– 15˚C) (Heller 1968; Straude 1987). Bibliography Larva: Since most amphipods are direct developing, they lack a definite larval stage. 1. BARNARD, J. L. 1954. Marine Instead, this young developmental stage amphipoda of Oregon. Oregon State resembles small adults (e.g. Fig. 39.1, Wolff Monographs, Studies in Zoology. No. 2014). 8:1-103. Juvenile: Sexual maturity is reached at four 2. —. 1965. Marine amphipoda of the months in water temperatures from 8–12˚C. family Ampithoidae from Southern Female oostegites appear after the fifth molt California. Proceedings of the U.S. and male genitals are apparent after the Natural Museum. 118:1-46. second molt. Sexual maturity is reached by 3. —. 1975. Phylum Anthropoda: the sixth or seventh molt in males and the Crustacea, Amphipoda: Gammaridea, tenth molt in females (Heller 1968). p. 313-366. In: Light's manual; Longevity: intertidal invertebrates of the central Growth Rate: Amphipod growth occurs in California coast. S. F. Light, R. I. conjunction with molting where the Smith, and J. T. Carlton (eds.). exoskeleton is shed and replaced. Post-molt University of California Press, individuals will have soft shells as the cuticle Berkeley. gradually hardens (Ruppert et al. 2004). 4. BEST, R. J., N. C. CAULK, and J. J. Time between molts increases with age and STACHOWICZ. 2013. Trait vs. averages 49 days in mature female A.