Leptochelia Spp
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Phylum: Arthropoda, Crustacea Leptochelia sp. Class: Multicrustacea, Malacostraca, Eumalacostraca Order: Peracarida, Tanaidacea, Tanaidomorpha A green tanaid Family: Paratanaoidea, Leptocheliidae, Leptocheliinae Taxonomy: The taxonomic history of Lepto- length. British Canadian species were report- chelia dubia and L. savignyi is confusing and ed to 4.5 mm (Fee 1927). remains to be resolved. In 1842, Krøyer de- Color: Transparent white to light green with scribed Tanais dubia and Tanais savignyi, some specimens bearing slight orange tinge the former species possessing one less seg- (Kozloff 1993; Cohen 2007). Brightly colored ment on the uropod endopod. These spe- females were found in early spring (South cies were later transferred to the new genus Slough of Coos Bay) that had red striped an- Leptochelia based on their elongate cheli- tennae. Males found in August were almost ped morphology. Due to morphological dis- transparent. parity between males and females, some General Morphology: Tanaids resemble Leptochelia females were described as new small, elongated and dorso-ventrally flattened species, including the genus Paratanais. lobsters with claws that extend anteriorly. Eventually, most of the variation between Their bodies can be divided into three sec- individuals (males and females) of newly de- tions, a cephalothorax (cephalon and first two scribed species was determined to be intra- pereonites), a thorax or pereon (including specific and species were synonymized un- pereonites 3–8) and a pleon (abdomen), der the “L. dubia group” (= “Leptocheliae- consisting of pleonites, with the posterior- Group 2”, Lang 1973 in Ishimaru 1985), most fused with the telson (pleotelson), and which included L. savignyi, among others. five pairs of pleopods as well as a single pair This group encompasses a wide geographic of uropods (see Plate 253A, Cohen 2007). distribution (Miller 1968) and it is likely com- Leptochelia dubia is a tube dweller (Cohen posed of several cryptic species (Cohen 2007) and resembles a slender isopod (see 2007; Jarquin-Gonzalez et al. 2015). In Fig. 340, Kozloff 1993). 2010, Bamber redescribed L. savignyi to in- Cephalon: Head narrows anteriorly and is clude many of the species previously in the fused with first two thoracic segments “L. dubia group”, but the full synonymy of the (Tanaidacea) (Fig. 1). two species is still uncertain. Because the Eyes: Stalked, large, and anterolateral name L. savignyi is older, there is also cur- (Figs. 1, 2). rent debate around which name should be Antenna 1: Male first antenna is long, the senior synonym (Cohen 2007; Bamber and has flagellum with seven articles (Fig. 2). 2010). Until the taxonomy is resolved we The female first antenna, on the other hand, is will use the name Leptochelia sp., but for the short, and consists of three articles (Figs. 1. sake of clarity we include species names 4). used by authors we cite. Antenna 2: Male second antenna is shorter than the basal article of the first Description antennae and consists of four articles (Fig. 2). Size: Individuals are rather small, up to 1 cm The female second antenna is longer than in length. The illustrated specimen (from that of the male, also with four articles (Fig. South Slough of Coos Bay) was 6 mm in 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. Leptochelia sp. 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. 1). orders proposed by Sieg (1980) include Mouthparts: Fused in males, and Apseudomorpha, Neotanaidomorpha and the can be dissected in females. Mandible is Tanaidomorpha, to which Leptochelia be- without palp (Tanaidomorpha, Fig. 3). longs. Members of the Apseudomorpha and Carapace: Tanaidomorpha occur locally (Cohen 2007). Chelipeds: Chelipeds are very Apseudomorpha species are not tube dwell- prominent, but sexually dimorphic. Male ers, they have a biramous flagellum of the first chelipeds are long and slender and with antenna, they sometimes lack pleopods, they carpus longer than basal article of the have mandibles with palps (3-articulated), and firstantenna (Figs. 2, 5). The propodus is the marsupium in females in composed of shorter than the fingers, which have two four pairs of oostegites only. Conversely, the teeth on the inner side (Fig. 5). Female Tanaidomorpha are usually tube-dwellers and chelipeds are short and heavy (Figs. 1, 6). are characterized morphologically by an un- Pereon: Consists of six uniform segments branched flagellum of the first antenna, man- (Fig. 1). dibles without palps, the presence of pleo- Pereopods: Six pairs plus the ante- pods, and a marsupium consisting of 1–4 rior chelate gnathopods (see chelipeds). A pairs of oostegites. small and inconspicuous penal process is Within the Tanaidomorpha there are at attached between the last pair of these legs least two local families, the Tanaidae and the in the male. Leptocheliidae (see Cohen 2007). The Tanai- Pleon: Consists of five similar segments dae are characterized by 3–5 pleonites plus a and a telson (Fig. 1). pleotelson and three pairs of pleopods, while Pleopods: Five pleopod pairs are bi- Leptocheliidae species have five pleopods. ramous and leaf-like. The genus Leptochelia is the only one Uropods: Both sexes have biramous uro- in the family Leptocheliidae occurring locally, pods, with exopodite very small and but the number of species is currently un- endopodite consisting of five articles (Fig. 7). known. Leptochelia dubia is suspected to be Pleotelson: Fused with posterior pleonite a complex of several species and may or may and bears medial posterior point (Fig. 1). not be synonymized with L. savignyi (Cohen Sexual Dimorphism: The first antenna is 2007) (see Taxonomy). Leptochelia savignyi longer in males than females, while the op- from Puget Sound, has four (sometimes six) posite is true for the second antenna. Cheli- segments in the endopodite of the uropod peds are long and slender in males (Fig. 5) (Kozloff 1974), has larger eyes and stubbier and short and stout in females (Fig. 6) first antennae than does L. dubia (Lang (Kozloff 1993), a character that lead many 1957). In L. savignyi the first free thoracic taxonomists to describe them as separate segment is shorter than the others, but they species (see Taxonomy). are fairly equal in L. dubia. The male cheli- Possible Misidentifications peds of the two species are almost identical. The Tanaidacea differ from the close- For re-description of L. savignyi, see Bamber ly related Isopoda in the number of pereon- 2010. Leptochelia filum, another Puget ites generally present: six in tanaids and Sound species is small (2.5 mm), white, and seven in isopods. In addition, tanaids have found at 37 meters sandy benthos, which is a jointed uropod branch and pair of cheli- quite a different habitat from that of L. dubia. peds anteriorly. The three tanaidacean sub- The endopodite of the uropod in this species has 3–4 articles, and not five as in L. dubia. 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] Ecological Information dubia exhibited a positive response to the Range: Type locality is off Brazil (Bamber presence of mussel mats created by the non- 2010). Cosmopolitan (see Miller 1968) and native mussel Musculista senhousia, poten- is almost certainly an assemblage of several tially due to the additional structure and sub- divergent species (Cohen 2007; Jarquin- strate the mats provide for tube building Gonzalez et al. 2015). Northwest distribu- (Crooks and Khim 1999). tion from Puget Sound, Washington to Abundance: The dominant invertebrate, southern California (Cohen 2007). when observed (e.g., Metcalf Preserve) and Local Distribution: In Coos Bay at Metcalf can be present in enormous numbers (Kozloff preserve and South Slough. Also found at 1993). In False Bay, San Juan Island, Wash- Tillamook Bay (Forsberg et al. 1977). ington, L. dubia was an abundant species, Habitat: A tube-dweller, L. dubia is found in with average density 416 to 2,600 individuals flimsy slime tubes much like those of amphi- per sediment sample (100 square cm by 14 pod Americorophium (see A. brevis, this cm deep, Brenchley 1981). Average densities guide), in a substrate of mud and wood can be very high and were reported to be chips (e.g. Metcalf Preserve). Additional greater than 30–50,000 individuals per square habitats include dead coral (Richarson 1902; meter (Tomales Bay, California, Mendoza Lewis 1998), sponge beds (at 45 meters, 1982; Friday Harbor, Washington, Highsmith Fee 1927), within sand in the strand line at 1983). low tide (Hatch 1947), and near the water Life-History Information surface on hydroids and algae (Fee 1927). Reproduction: Tanaidaceans are gonochor- The upper limit of sand grain size is 200 µm istic, sequentially (protogynous) or simultane- L. (Wieser 1959). Higher abundances of ously hermaphroditic (Highsmith 1983; Boyko dubia were observed in areas of and Wolff 2014) and sexual reversal may be intermediate or low pH (see Tables 1–2, determined by environmental factors (e.g. Leptochelia savignyi Cigliano et al. 2010). temperature, Masanuri 1983; Highsmith was found at the ends of empty spionid 1983). Reproduction in tanaidaceans, like Dipolydora armata polychaete ( ) burrows or isopods, is direct and proceeds within the fe- amongst calcareous hydrozoan (Millepora male brood chamber (i.e. marsupium) to a lar- complanata ) branches in Barbados (Lewis val form, called a manca that resembles a 1998). Individuals were reported to be small adult.