Chthamalus hedgecocki Pitombo & Burton, 2007 Figs 2C and 9–11 BC Chthamalus fissus Hedgecock, 1979: 210, Table 2. [5] Chthamalus hedgecocki Pitombo & Burton, 2007: 4, figs 2–7. [12]—Wares et al., 2009: Table 2 [14] Specimens examined. AJS-3, 15 specimens, intertidal shores, Point Lobos,Todos Santos, Baja California Sur, Mexico, 23° 24.8' N, 110° 57' W, 4 Nov 1978; TEPE78-14, 10 specimens, exposed rocks and sheltered boulders, Isla Sacrificios, Oaxaca, Mexico, 15° 40.8' N, 96°14.6' W; TEPE78-35, 30 specimens, La Paz, Promenade, Baja California Sur, Mexico, 24° 09' N, 110° 15' W, 18 April, 1978. Diagnosis. Chthamalus with shell pink-purple to brown externally (white in older and eroded specimens). Outer side of cirrus I with an array of long serrulate setae (one on each segment) on the anterior ramus. Posterior ramus of cirrus I lacks bidenticulate setae. Cirrus II has bidenticulate setae with basal guards on one or two of the distalmost segments of the posterior ramus and the distalmost segment of the anterior ramus. Tergoscutal flaps dull orange-brown in colour, when alive. COI sequence (Gene Bank Numbers: KU356704—KU356705). Description. External shell surface pink-purple to white in eroded or bleached specimens, surface ribbed but ribs do not extend to apex (Fig 2C). Inside of shell pale brown to white. Orifice elliptical. Scutum and tergum slightly asymmetrical, scutum and tergum articulated transversely (Fig 9A). In older specimens the outer surface of the scutum and tergum was eroded, horizontal growth lines visible on the basal region (Fig 9B–9F). Scutum triangular, tergal margin about half the length of the basal margin, articular ridge not, or seldom, extending beyond the tergal margin, articular furrow deep. Occludent margin without teeth, smooth. Basal margin slightly convex, with obvious lateral depressor muscle crest (Fig 9). Tergum trapezoid, scutal margin slightly convex, spur wide and blunt, carinal margin with 4–5 lateral depressor muscle crests (Fig 9B and 9E). Segment counts on cirri I-III were based on five specimens collected from Point Lobos, Baja California Sur, Mexico (AJS-3). Segment counts on cirri IV-VI were based on a single specimen from Point Lobos, Baja California Sur, Mexico (AJS-3) (Table 4). Cirrus I: posterior ramus 5–7 segmented, anterior ramus 7- to 9-segmented. Outer side of anterior ramus with a longitudinal array of long, serrulate setae, a single seta on each segment, posterior ramus setae serrulate, no bidenticulate setae (absent from all specimens examined, Fig 10A). Cirrus II: posterior ramus 5- to 6-segmented, anterior ramus 5- to 6-segmented, first or first and second most distal segments of the posterior and the most distal segment of the anterior ramus with bidenticulate setae with basal guards (Fig 10B and 10D, Table 4). Cirrus III: anterior and posterior rami similar in length, anterior ramus 13- to 19-segmented, posterior ramus 14- to 17-segmented, intermediate segments have 3 pairs of long setae and 2 pairs of short simple setae (Fig 10E, Table 4). Cirrus IV and V: anterior and posterior rami 16-segmented, intermediate segments of both rami carry 3 pairs of long serrulate setae and 2 pairs of short simple setae (Fig 10F and 10G). Cirrus VI: anterior and posterior rami 19-segmented (Fig 10H). Maxilla with serrulate setae (Fig 11A). Maxillule notched, two large setae above notch, notch wide and shallow, with 4–5 setae in notch, region below notch protuberant, with > 14 setae along the protuberant cutting edge (Fig 11B). Mandible has 4 major teeth, fourth tooth bi-dentate (Fig 11C). Pecten long, with 24 very fine teeth, inferior angle with a pair of pointed teeth (Fig 11D). Mandibular palp rectangular, with serrulate setae on superior margin and tip (Fig 11E and 11F). Labrum with V-shaped cutting edge, without sharp teeth on either side of the cutting margin, central part of the notch carries dense setae (Fig 11G and 11H). Penis without basi-dorsal point. Distribution. Southward from 23° 39' N inside the Gulf of California, on the east coast, and 32° 52' N on the western outer coast of the Baja California Peninsula. The southern limit is north of 15° N on the Mexican Pacific coast. The type material of Chthamalus hedgecocki Pitombo & Burton, 2007 came from Punta Camarón, Mazatlan, Sinaloa, Mexico (23° 14' 15'' N, 106° 26' 45'' W) attached to rocks on a wave exposed shore, upper midlittoral zone. The geographical distribution was stated by Pitombo and Burton to extend from Baja California to Acapulco in southern Mexico (16° 50' 19'' N). Remarks. Pitombo & Burton [12] reported that the outer surface of the tergum in C. hedgecocki posesses a weak longitudinal furrow, frequently only on one plate. In the present study of specimens from Point Lobos, Baja California, the tergum of C. hedgecocki is smooth externally and without any longitudinal furrows. The arthropodal characters of C. hedgecocki in the present study agree with the descriptions in Pitombo & Burton [12]. The shallow longitudinal furrow in at least one of the the terga of C. hedgecocki may be a variable character and may not be a diagnostic character for species identification.

{"references": ["5. Hedgecock D. Biochemical genetic variations and evidence of speciation in Chthamalus barnacles of the Tropical Eastern Pacific Ocean. Marine Biology. 1979; 54: 207 - 14.", "12. Pitombo FB, Burton R. Systematics and biogeography of Tropical Eastern Pacific Chthamalus with descriptions of two new species (Cirripedia, Thoracica). Zootaxa. 2007; 1547: 1 - 30.", "14. Wares JP, Pankey MS, Pitombo F, Daglio LG, Achituv Y. A \" Shallow Phylogeny \" of Shallow Barnacles (Chthamalus). PLoS One. 2009; 4: e 5567. doi: 10.1371 / journal. pone. 0005567 PMID: 19440543"]}

Published as part of Benny K. K. Chan, H. - N. Chen, P. R. Dando, A. J. Southward & E. C. Southward, 2016, Biodiversity and Biogeography of Chthamalid Barnacles from the North-Eastern Pacific (Crustacea Cirripedia), pp. 1-51 in PLoS ONE 11 (3) on pages 14-21, DOI: 10.1371/journal.pone.0149556, http://zenodo.org/record/1161582