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Petrolisthes Cinctipes Class: Malacostraca Order: Decapoda Section: Anomura, Hippoidea the Flat Porcelain Crab Family: Porcellanidae

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Petrolisthes Cinctipes Class: Malacostraca Order: Decapoda Section: Anomura, Hippoidea the Flat Porcelain Crab Family: Porcellanidae Phylum: Arthropoda, Crustacea Petrolisthes cinctipes Class: Malacostraca Order: Decapoda Section: Anomura, Hippoidea The flat porcelain crab Family: Porcellanidae Taxonomy: Petrolisthes cinctipes is and has short and not reaching upper margin of been a widely used name for this species. carapace. There are, however, several junior synonyms Mouthparts: The mouth of decapod including Porcellana cinctipes, Porcellana crustaceans comprises six pairs of rupicola, and Petrolisthes rupicolus (for all appendages including one pair of mandibles synonyms see Haig 1960; Wicksten 2011). (on either side of the mouth), two pairs of maxillae and three pairs of maxillipeds. The Description maxillae and maxillipeds attach posterior to Size: Individuals up to 24 mm in length the mouth and extend to cover the mandibles (carapace width) (Puls 2001; Wicksten 2011). (Ruppert et al. 2004). Second maxillipeds in The illustrated specimen (from Coos Bay) is P. cinctipes are highly developed for filter 14 mm in length and weighs 1.7 g. feeding (see Food) with long fine hairs and Color: Dark blue-brown and somewhat specialized shape for channeling water iridescent (see Plate 20, Kozloff 1993). currents (Fig. 4). The color of the palps of Antennae dark red, maxillipeds bright red- maxilliped three are of taxonomic importance: orange and legs blue banded with white blue in P. eriomerus and orange in P. (Schmitt 1921). White comma-like marks are cinctipes (Kozloff 1993; Kuris et al. 2007). sometimes present ventrally and chelipeds Carapace: Round with carapace front bear a red spot at dactyl base, while walking triangulate (Petrolisthes, Haig 1960). legs have a yellow median band on propodus. Carapace surface is finely granulate and not Dactyls yellow with narrow brown band. rough. No epibranchial (anterolateral) spines Individuals near molting are blue in color and epimera and lateral portions of carapace (Wicksten 2011). are entire (Figs. 1, 2). Carapace about as General Morphology: The body of decapod long as wide (Wicksten 2011). crustaceans can be divided into the Frontal Area: Triangular and strongly cephalothorax (fused head and thorax) and deflexed with conspicuous median groove abdomen. They have a large plate-like (Fig. 1). carapace dorsally, beneath which are five Teeth: pairs of thoracic appendages (see chelipeds Pereopods: Waking legs 2–4 with a and pereopods) and three pairs of few coarse spines on dactyl, propodus and maxillipeds (see mouthparts). The body of carpus, but not on merus (Fig. 1). Merus of the Porcellanidae is crab-like and convex third leg is inflated and carpus is without longitudinally with small fifth legs resting on setae while propodus and dactyl bear setae. carapace (Fig. 1) and the abdomen and Fifth legs small, elevated and rest on associated appendages are reduced and carapace (Figs. 1, 3). folded ventrally. The body and chelae of Chelipeds: Equal (or almost), broad Petrolisthes are flattened (Kuris et al. 2007). and flattened, not thick and rough Cephalothorax: (Petrolisthes, Schmitt 1921; Kuris et al. 2007), Eyes: The eyestalks of P. cinctipes covered with fine granules (as in carapace) contain neurosecretory cell bodies (z-organs) but without setae. Carpus almost invariably 1 that regulate regeneration, molting and oocyte 1/2 times longer than wide and anterior and maturation (Kurup 1964a). posterior margins converge distally (Schmitt Antennae: Very long, and often 1921; Kuris et al. 2007) (Fig. 1). Posterior folded posteriorly over carapace sides (Fig. margin with ridge of tubercles flanked by teeth 1). First (basal) joint of antennal peduncle is distally. Prominent lobe at inner angle (P. Hiebert, T.C. 2015. Petrolisthes cinctipes. 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/1794/12729 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] cinctipes, Kuris et al. 2007) (Fig. 1). A short long) and the carpus margins are parallel, not tuft of hair between fingers present ventrally, converging. Also, there is no prominent lobe but chelae are generally hairless (Figs. 1, 2). at the inner angle and the carpus has Merus with conspicuous lobe on anterior scattered tubercules, not a finely granulated margin. (Wicksten 2011). surface as in P. cintctipes. Ventrally, the Abdomen (Pleon): Abdomen symmetrical, outer edge of the maxillipeds in P. eriomerus short and permanently folded under thorax. is bright blue, not red orange (Kozloff 1993; Seven abdominal plates (Petrolisthes) (Figs. Kuris et al. 2007). These two species exhibit 1, 2). a non-overlapping vertical distribution, where Telson & Uropods: Seventh plate of telson P. eriomerus occurs in the low intertidal and forms tail fan (Fig. 2). Uropods attached to P. cinctipes is found in the mid to high abdominal segment five. intertidal (Jensen and Armstrong 1991). Sexual Dimorphism: Not obvious P. cabrilloi, P. manimaculis and P. superficially. Inside telson, males have single rathbunae are all reported from California: pleopods on abdominal plate two and females Petrolisthes cabrilloi from Morro Bay, have long, branched pleopods on plates 3–5 California south to Baja California, Mexico (not shown). and apparently replaces populations of P. cinctipes south of Point Conception, Possible Misidentifications California; P. manimaculis from Bodega Bay, Porcelain crabs (Porcellanidae) are flattened California south to Baja California, Mexico; P. dorso-ventrally and are often found in small rathbunae from Monterey, California to Isla cracks and crevices. Their third maxillipeds Guadalupe, Mexico (Wicksten 2011). bear long setae, which they use to filter feed and their fifth walking legs are modified into Ecological Information brushes for grooming. There are two genera Range: Type locality is erroneously indicated of porcelain crabs in our area, Petrolisthes as in Hawaii, but is likely to be near Monterey, and Pachycheles. Members of the California (Wicksten 2011). Known range Pachycheles have a thick, rough body and includes British Columbia to Point chelae, chelae are unequal, tuberculate or Concepcion, California and also islands granular and hairy, not smooth. Furthermore, offshore of southern California, and Baja the carpus of the chela is as long as broad, California (Haig 1960). not longer than broad as in Petrolisthes. Local Distribution: Outer, more marine There are three local species: P. holosericus, portions of large estuaries. Occurs locally in P. pubescens and P. rudis (Kuris et al. 2007). Coos Bay (e.g. Pigeon Point) and in Netarts Petrolisthes species, on the other Bay. hand, have a flattened body and chelae, Habitat: Protected, semi-protected rocky chelae of equal size with carpus longer than it coasts under rocks and amongst mussel beds is wide. Petrolisthes cinctipes is recognizable (Ricketts and Calvin 1971; Kuris et al. 2007). by characteristics of the cheliped carpus. The Prefers open shores and clear water (Haig carpus has a long anterior lobe that extends 1960) and is not tolerant of sand and silt more than 1/4 total carpus length, is smooth (Jensen and Armstrong 1991; Wicksten and hairless and with margins that converge 2011). distally (Kuris et al. 2007). Five Petrolisthes Salinity: Collected at salinities of 30. species are reported to occur from central Temperature: A mid to high intertidal California to Oregon including P. cinctipes, P. species, P. cinctipes is exposed to a wide cabrilloi, P. eriomerus, P. manimaculis and P. range of temperature (0–32˚C, Stillman and rathbunae. Somero 2000). Recent research involving Of those, P. eriomerus is superficially physical factors associated with climate quite like P. cinctipes (Kozloff 1993). This change has used P. cinctipes as a model crab lives under rocks in gravelly substrates organism (e.g. Somero 2010). Stress by and is a little smaller than P. cinctipes. The thermal variation, more than other physical carpus of the chelipeds in P. eriomerus is factors (e.g. pH, salinity), negatively effects P. twice as long as wide (not 1 1/2 times as cinctipes (Paganini et al. 2014). However, Hiebert, T.C. 2015. Petrolisthes cinctipes. 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. when acclimated for a short period of time (6 (Ricketts and Calvin 1971) with a long spine hrs), P. cinctipes can increase to discourage predators. Other characters of thermotolerance (Ronges et al. 2012). zoeal morphology include a telson posterior Research involving elevated pCO2, salinity margin that is rounded and with long plumose and lower pH, all of which simulate predicted setae. Pachycheles and Petrolisthes species physical changes associated with climate can be distinguished by the presence of change, have focused on P. cinctipes life- terminal brushes on telson setae, in that history stages (e.g. Miller et al. 2014). Long Pachycheles species have only two and exposure (40 d) to low pH reduced juvenile Petrolisthes species have brushes on all survival and heart rate. Furthermore, setae (Puls 2001). The megalopa of embryonic volumes do not increase at a Petrolisthes species have long, slender normal
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