Chthamalus, Ranzani, 1817

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), PLoS ONE 11 (3), pp. 1-51 : 29-35

publication ID	https://doi.org/ 10.1371/journal.pone.0149556
DOI	https://doi.org/10.5281/zenodo.4426658
persistent identifier	https://treatment.plazi.org/id/03D887BE-6317-842C-C779-49DE0A34FE20
treatment provided by	Plazi
scientific name	Chthamalus
status

Treatment

Chthamalus View in CoL View at ENA panamensis Pilsbry, 1916

Figs 2E and 2F View Fig2 and 18–22 View Fig18 View Fig19 View Fig20 View Fig21 View Fig22

Chthamalus View in CoL panamensis Pilsbry, 1916: pp 319–320, Plate 75 fig 2–2e [ 2]

Specimens examined. ANSP(Crustacea)-2008, type collection of 7 syntypes deposited by Pilsbry 1916, Quarantine Island, Panama (= Naos Island), the intact specimen illustrated in Pilsbry’ s Plate 75, fig 2a is selected by the present authors as the Lectotype; AJS-1970. 12 specimens, rock ledges, Balboa Statue , Panama City, Panama. 8° 58.1' N, 79° 32' W, 31 Oct 1970; PWG-1, 10 specimens, intertidal rocks, 200 m N of Naos Island on the west side of Avenida Amador, 8°58.12' N, 79° 31.81' W, 3 Feb 1979.

Diagnosis. Chthamalus with a deep longitudinal furrow on outer surface of the tergum, scutal margin of tergum straight. Bidenticulate setae absent from cirrus I. Outer surface of anterior ramus of cirrus I with a longitudinal array of setae. Cirrus II, distalmost segment of both anterior and posterior rami bears bidenticulate setae with basal guards, anterior ramus of cirrus III is about 1.5 times longer than the posterior ramus. Tergoscutal flaps orange. COI sequence (Gene Bank Numbers: KU356706 View Materials — KU356708 View Materials ).

Description. Shell pink to purple in unbleached or uneroded specimens, otherwise white, with six plates ( Figs 2E and 2F View Fig2 and 18A and 18B View Fig18 ). Surface with ribs extending to the apex. Orifice elliptical. Scutum and tergum articulated slightly obliquely. Scutum triangular, basal margin twice the length of the tergal margin, external surface with horizontal growth lines, and the upper portion often eroded, tergal margin with shallow articular ridge, not extending beyond the tergal margin, occludent margin straight to slightly convex, with teeth on proximal 1/3 of the margin in uneroded specimens ( Fig 18C and 18D View Fig18 ). Adductor muscle pit oval, not extending to basal margin. Lateral depressor muscle pit deep and smooth ( Fig 18D–18F View Fig18 ). Tergum triangular to trapezoid, external surface with horizontal striations and a deep longitudinal furrow is visible in the basal region ( Fig 18D–18F View Fig18 ). Such a furrow can be observed from above through the orifice of uneroded, undissected specimens ( Fig 18A and 18B View Fig18 ). Inner surface of tergum smooth, scutal margin straight, spur flat and not obvious, depressor muscle crests 3–4 ( Fig 18 View Fig18 ).

The original description of Chthamalus panamensis Pilsbry, 1916, (pp. 219–320 and Plate75 fig 2, 2a, 2b, 2c, 2d and 2e) describes only the shell and opercular plates (also see Fig 18B View Fig18 ). Pilsbry’ s figure of the exterior of the tergum (Plate 75 fig 2e) is closely similar to the exterior of terga in our new material. The following description of the arthropodal characters is based on new material [Avenida Amador, Naos Island].

Quantitative data on segments counts in cirrus I-III were based on five specimens collected from Avenida Amador, Naos Island (PWG-1). Segment counts on cirri IV-VI were based on a single specimen from Avenida Amador, Naos Island (PWG-1) ( Table 4 View Table4 ). Cirrus I: posterior ramus 5- to 7-segmented, anterior ramus 6- to 8-segmented, outer surface with a longitudinal array of long setae, with almost one seta per segment, serrulate setae common on both rami ( Figs 19A and 19B View Fig19 and 20A–20D View Fig20 ). Cirrus I without bidenticulate setae (absent from all specimens examined), pappose setae on basipodite ( Fig 20E View Fig20 ). Cirrus II: posterior ramus 5 to 7 segments, anterior ramus 6 to 8 segments ( Figs 19C View Fig19 and 20G View Fig20 ), the most distal segment of each ramus with bidenticulate setae with basal guards, serrulate setae common on both rami ( Figs 19C and 19D View Fig19 and 20G–20I View Fig20 , Table 4 View Table4 ). Pappose setae on basipodite ( Fig 20J and 20K View Fig20 ). Cirrus III: posterior 12- to 16-segmented, anterior ramus 16- to 22-segmented, 1.4 to 1.5 times the length of the anterior ramus ( Fig 19E View Fig19 ), intermediate segments bear 3 pairs of long and 1 pair of short setae ( Figs 19E View Fig19 and 20L–20N View Fig20 ). Cirrus IV: anterior and posterior rami similar in length ( Fig 19F View Fig19 ), anterior and posterior rami 16 segmented ( Figs 19F View Fig19 and 20O and 20P View Fig20 ). Cirrus V: anterior and posterior rami 16-segmented ( Fig 19G View Fig19 ). Cirrus VI: anterior ramus 19-segmented, posterior ramus 20-segmented ( Figs 19H View Fig19 and 20Q View Fig20 ). The intermediate segments of cirri IV-VI bear three pairs of long and one or two pairs of short simple setae ( Figs 19F–19H View Fig19 and 20S and 20R View Fig20 ).

Maxilla bilobed, with dense serrulate setae on each lobe ( Figs 21A View Fig21 and 22A–22C View Fig22 ). Maxillule notched, notch weak, two large setae above notch, 10 setae below notch ( Figs 21B View Fig21 and 22D and 22E View Fig22 ). Mandible has 4 major teeth, second to fourth teeth bidenticulate, pecten with 21 very small teeth, inferior angle tipped with 3 pointed teeth ( Figs 21C and 21D View Fig21 and 22F–22K View Fig22 ). Mandibular palp rectangular, with long simple setae on tip and serrulate setae on superior margin ( Figs 21E and 21F View Fig21 and 22L, 22M and 22N View Fig22 ). Labrum concave, with 6 or 7 small fine teeth on cutting edge ( Figs 21G and 21H View Fig21 and 22O and 22P View Fig22 ).

Penis without basi-dorsal point.

Distribution. Pacific coast of Central America from about 14° N to 8° 15' N (southern limit unknown).

Remarks. Specimens of C. panamensis collected for the present study agreed with the syntypes of C. panamensis described by Pilsbry [ 2] in having a deep groove on the outer surface of the tergum, which is the key diagnostic feature of C. panamensis. This morphological feature of the tergum was also reported in Pitombo & Burton [ 12].

The sympatric C. newmani sp. nov is distinguishable from C. panamensis in situ by its lack of deep tergal grooves. In addition, it has has brown tergo-scutal flaps while those of C. panamensis are orange. The flaps are visible in the living barnacle when the orifice is open under water ( Fig 2E and 2F View Fig2 ). Arthropodal character differences are: Cirrus I of C. newmani has bidenticulate setae, Cirrus I of C. panamensis does not. Cirrus III of C. newmani has equal rami. Cirrus III of C. panamensis has unequal rami. This feature of cirrus III in C. panamensis was not reported by Pilsbry [ 2] or Pitombo & Burton [ 12].