Chthamalus alani, Chan, 2016

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 : 8-13

Chthamalus alani nom. nov.

urn:lsid:zoobank.org:act:4C460612-D362-49BA-9A20-F2895C4CE1F5

the authority for this species name change rests with BKK Chan

Figs 2A and 2B and 3–5

Chthamalus southwardorum Pitombo & Burton, 2007: 9 , figs 9–14 [ 12]

Chthamalus southwardorum A.—Wares et al., 2009: Table 1 . [ 14]

Etymology. Pitombo & Burton [ 12] stated explicitly that Chthamalus southwardorum is named “in honor of Dr A.J. Southward, for his extensive contribution to the knowledge of chthamalids and his careful collecting during the Tropical eastern Pacific Expedition”. Unfortunately, the suffix -orum indicates “for men or for man (men) and woman (women) together” (ICZN, 4th edition, 1999 Article 31.1.2). Since there is clear evidence of a lapsus calami in the original publication (ICZN ART 32.5.1) the name C. southwardorum is not admissible under ICZN Art. 21.13 and has to be treated as an incorrect original spelling that should be corrected to southwardi , taking the authorship and date of Pitombo & Burton [ 12]. However, Chthamalus southwardi Pitombo & Burton, 2007 is a junior primary homonym of Chthamalus southwardi Poltaruka, 2000 and therefore an invalid name (ICZN Art 57.2) and so a new replacement name is required for C. southwardorum . In the present study, I (BKKC) rename C. southwardorum as Chthamlaus alani , again in honour of Prof. Alan Southward, but using his first name, for his contributions to barnacle distribution, ecology and taxonomy.

Specimens examined. AJS-2, 10 specimens, high intertidal shores, La Paz Bay, 24° 13' N, 110° 18.6' W, 3 Nov 1978; AJS-3, 7 specimens, intertidal shores, Point Lobos, Todos Santos, Baja California Sur, Mexico, 23° 24.8' N, 110° 57' W, 4 Nov 1978; TEPE78-36, 10 specimens, Ocean Front, Mazatlan, Sinaloa, Mexico, exposed rocky shores with large boulders, 23° 11.7' N, 106° 25.5' W, 19 April 1978.

Diagnosis. Chthamalus with cirrus I having bidenticulate setae with or without basal guards on the distalmost segment of the posterior ramus and cirrus II having bidenticulate setae with basal guards on the two distalmost segments of the posterior ramus and the distalmost segment of the anterior ramus. Tergoscutal flaps orange-brown in colour when alive. COI sequence (Gene Bank Number KU356723 ).

Description. Shell depressed, sutures between plates visible ( Fig 2A and 2B ). External surface white and smooth, sheath white, with ribs at the basal region, not extending to the apex ( Fig 2A and 2B ). Internal colour of shell white. Orifice oval, scutum and tergum articulated with a marked angle ( Figs 2A and 2B and 3D ). Tergoscutal flaps orange-brown when alive ( Fig 2A and 2B ), colour fades out when preserved in ethanol or formalin. Scutum triangular, basal margin about twice as long as tergal margin ( Fig 3 ). Tergal margin with a wide and elevated articular ridge, ridge extending beyond the tergal margin, articular furrow wide. Occludent margin straight, without teeth. Adductor muscle pit oval and deep, not extending to the basal margin. Lateral depressor muscle scar deep and smooth ( Fig 3 ). Tergum trapezoid, external surface smooth near the apex, basal region with growth lines or striations, spur wide and not obvious, basal margin with 4 rostral depressor muscle crests ( Fig 3 ).

Segment counts on cirri I-III were based on five specimens collected from Mazatlan, Mexico (TEPE-78-36). Segment counts on cirri IV-VI were based on a single specimen from Mazatlan, Mexico ( Table 4 ). Cirrus I: posterior ramus 5 to 6-segmented ( Fig 4A ), the distalmost segment bears bidenticulate setae with or without basal guards ( Fig 4B ), serrulate type setae common on all segments of the rami, anterior ramus 6 to 8, serrulate type, setae common on all segments ( Fig 4A , Table 4 ). Cirrus II: posterior ramus 4 to 7-segmented, the two distalmost segments bear bidenticulate setae with basal guards, anterior ramus 5- or 6-segmented, one or two of the distalmost segments have bidenticulate setae with basal guards, serrulate type setae common on both rami ( Fig 4C and 4D , Table 4 ). Cirrus III: anterior and posterior rami similar in length (anterior and posterior rami length ratio = 0.9 ± 0.06), posterior ramus 11 to 16-segmented, anterior ramus 11 to 16-segmented ( Fig 4E , Table 4 ). Cirrus IV: both anterior and posterior rami 16-segmented ( Fig 4F ). Cirrus V: posterior ramus 18-segmented, anterior ramus 19-segmented ( Fig 4G ). Cirrus VI: posterior ramus 18-segmented, anterior ramus 19-segmented ( Fig 4H ). Intermediate segments of both rami on cirri III-VI bear two pairs of long serrulate setae and three pairs of shorter simple setae ( Fig 4E–4H ).

Maxilla bilobed, serrulate setae on apex of both lobes and on superior margin ( Fig 5A ). Maxillule notched, two large setae above notch, notch small, 8 setae on cutting margin below notch, inferior angle protuberant with bundles of simple setae ( Fig 5B and 5C ). Mandible has 4 major teeth, fourth tooth bidenticulate, pecten with 16 small teeth, inferior angle tipped with two pointed teeth ( Fig 5D and 5E ). Mandibular palp rectangular, serrulate setae on all margins ( Fig 5F ). Labrum concave, with 6–7 small teeth on both sides of the cutting edge ( Fig 5G and 5H ).

Penis without basi-dorsal point.

Distribution. Northern limit probably at about 29° N inside the Gulf of California and 24° 40' N on the Pacific coast; southern limit unknown, but probably north of 15° N. The holotype and paratypes of C. southwardorum Pitombo & Burton, 2007 were collected in the San Cristovan river estuary, San Blas, Nayarit, Mexico (21° 30' 54'' N, 105° 15' 53'' W), attached to an oyster shell, low midlittoral zone. Pitombo and Burton stated that the distribution of C. southwardorum was from Bahía Magdalena, Baja California Sur, Mexico to Puerto Chicama, Peru, but they did not distinguish it from the new species C. newmani described below.

Figures

Fig2. LiveChthamalusspeciesphotographedunderwater.A,mixedpopulationsofCanisopoma(CAN),withwhite-edgedtergoscutalflaps,Balanus inexpectatatus(BI)withwhitetergoscutalflapsandChthamalusalaninom.nov.(CA)withorangetergoscutalflaps(fromLaPaz,BajaCalifornia).B,C.alani showingorangetergoscutalflaps(fromLaPaz).C,C.hedgcockishowingorangetergoscutalflaps(fromPointLobos,TodosSantos,BajaCalifornia).D, Chthamalusnewmanisp.nov.showingbrowntergoscutalflaps(fromFarfanPoint,Panama).E,F,mixedpopulationofC.panamensis(CP)showingorange tergoscutalflapsandC.newmani(CN)showingbrowntergoscutalflaps(E,BalboaStatue.PanamaCityandF,NaosIsland). doi:10.1371/journal.pone.0149556.g002

Fig3. Chthamalusalaninom.nov.A,B,lightstereomicroscopyshowinginnersideofpairedscutumandtergum,LaPazspecimen.C,scanningElectron Micrograph(SEM)showingtheinnersideofscutumandtergum,Mazatlanspecimen.D,pairedarticulatedscutumandtergum,aLaPazspecimen,showing theobliquearticulationoftheplates(a). doi:10.1371/journal.pone.0149556.g003

Fig4. Chthamalusalaninom.nov.Matzalan,Mexico.A,B,cirrusI,showingthepresenceofbidenticulatesetae(bi)withorwithoutbasalguards(bg), enlargedinB.C,D,cirrusII,showingthepresenceofbidenticulatesetae(bi)withbasalguards(bg)onthefirstfewsegments(indicatedbydoubleend arrows)inD.E,cirrusIII.F,cirrusIV.G,cirrusV.H,cirrusVI.IntermediatesegmentsofanteriorramiofcirriIII-VIareshownasinsertsinE-H.Scalebars in μm. doi:10.1371/journal.pone.0149556.g004

Fig5. Chthamalusalaninom.nov.Matzalan,Mexico.A,maxilla.B,maxillule.C,magnifiedviewshowingthenotchregionofmaxillule.D,mandible.E, fourthtooth,pectenandinferiorangleofmandible.F,mandibularpalp.G,labrum.H,cuttingmarginoflabrumshowingthefineteeth.Scalebarsin μm. doi:10.1371/journal.pone.0149556.g005

Tables

Table4. Segmentcounts(n=5individuals)ofChthamalusintheTropicalEasternPacificwaters.

	C. hedgecocki	C. anisopoma	C. alani	C. panamensis	C. newmani
Cirrus I: No. of segments in posterior ramus	5–7	6–7	5–6	5–7	6–7
Cirrus I: No. of segmentsin anterior ramus	7–9	7–8	6–8	6–8	8–9
Cirrus I: No. of segments in posterior ramus with bidenticulate setae	0 ± 0	1	1	0	1
Cirrus II: No. of segments in posterior ramus Cirrus II: No. of segments in anterior ramus Cirrus II: No. of segments in posterior ramus with bidenticulate setae with basal guards	5–6 5–6 1–2	5 6–7 4	4–7 5–6 2	5–7 6–8 1	5–7 7–8 3
Cirrus II: No. of segments in anterior ramus with bidenticulate setae with basal guards	1	2	1–2	1	2
Cirrus III: No. of segments in posterior ramus	14–17	13–14	11–16	12–16	17–19
Cirrus III: No. of segments in anterior ramus	13–19	13–19	11–16	16–22	18–23
Cirris III, anterior/posterior length ratio	0.9–1.0	0.8–1.2	0.8–0.9	1.4–1.5	0.9–1.2

Note: cirrus I of C. anisopoma has bidenticulate setae without basal guards, whilst cirrus I of C. alani nom. nov. and C. newmani sp. nov. has bidenticulate setae with or without basal guards. doi:10.1371/journal.pone.0149556.t004