Lepidonotus pilosus Treadwell, 1937: 141–143 Lepidonotus pomareae panamensis Hartman, 1939a: 44–46 Lepidonotus panamensis : Hartman 1948: 28 Chaetacanthus magnificus : Salazar-Vallejo et al . 1990: 215 Chaetacanthus pilosus : Salazar-Silva 2006: 146 Revision of Chaetacanthus Seidler, 1922 (Annelida, Phyllodocida, Polynoidae) Salazar-Silva, Patricia López-Sánchez, Daniel A. Salazar-Vallejo, Sergio I. Zootaxa 2020 2020-11-26 4885 3 395 422 69MLH (Treadwell, 1937) Salazar-Silva & López-Sánchez & Salazar-Vallejo 2020 Treadwell 1937 [151,650,834,861] Polychaeta Polynoidae Chaetacanthus Animalia Phyllodocida 16 411 Annelida species pilosus   Figures 14–16      Lepidonotus pilosus Treadwell, 1937: 141–143, Pl. 1, Figs. 1–7.     Lepidonotus pomareae panamensis Hartman, 1939a: 44–46, Pl. 6, Figs. 70–77 ( partim).     Lepidonotus panamensis: Hartman 1948: 28(n. status, partim).     Chaetacanthus magnificus: Salazar-Vallejo et al. 1990: 215, Fig. 37 ( non Grube, 1876).     Chaetacanthus pilosus: Salazar-Silva 2006: 146(reinst.).   Type material. Eastern Pacific.  Holotypeof  Lepidonotus pilosus Treadwell, 1937, AMNH 3531, Arena Bank, Gulf of California, Sta. 136, D-13 ( 23°29’ N 109° 24’ W),  20 Apr. 1936.  Holotypeof  Lepidonotus pomareae panamensis Hartman, 1939a, LACM 3, AHF-5, Poly 0039, Bahía Honda, Panama, off  North Island, R/ V VeleroIII, Sta. 863-  38, 54–90 m,  1 Mar.1938.   Additional material. Eastern Pacific, Panama. Onespecimen, LACM 863-38, off Bahía Honda,  54–90 m, rock sand mud, R/ V Velero, Sta.863-38, 07°45’35” N, 81°35’35” W,  26 Jan. 1939, identified as  Lepidonotus pomareae panamensisbut separated from holotype.   Diagnosis.  Chaetacanthuswith branchial filaments digitiform, bifurcated; elytra with abundant pedunculated macrotubercles and microtubercles, spinous, hemispherical, amber in colour, larger over the elytrophore and on first pair of elytra.   Description. Holotypeof  Lepidonotus pilosus(AMNH 3531) robust, 2.5 cm long, 1.3 cm wide, 26 segments; body homogeneously yellowish without spots, integument wrinkled. Prostomium longer than wide, slightly retracted into segment two; prostomial lobes laterally expanded. Two pairs of eyes, circular, dark, anterior pair on widest prostomial area, posterior pair hidden under anterior projection of segment two ( Fig. 14A). Facial tubercle long, slender. Median antenna with ceratophore thick, long, inserted frontally, at same level of lateral antennae, style missing. Lateral antennae with ceratophores thick, long, inserted frontally on prostomial lobes, styles missing. Palps robust, long, two times longer than prostomial length, tapered into filiform tips, surface with rows of papillae. Pharynx not everted. Tentacular segment not visible dorsally. Tentaculophores thick, long, inserted laterally to prostomium, with several chaetae; tentacular cirri missing. Second segment projected anteriorly over prostomium as a wide round lobe. First pair of elytrophores expanded laterally over tentaculophores, with large elytral scar. Segment three narrower than following ones. Elytral margin with fringe of abundant long papillae ( Fig. 14B), all with a distinctive bundle of papillae on posterior margin. Elytral surface with abundant spinous macrotubercles, and microtubercles. Macrotubercles pedunculate, distally hemispherical with abundant small spines, mostly scattered along elytral surface, but in first pair of elytra macrotubercles prominent, concentrated in elytral plug area ( Fig. 14C, D). Microtubercles hemispherical or tapered, tips subconical. Parapodia biramous, robust. Notopodia short. Neuropodia short, truncated, with acicular tips emergent ( Fig. 14E, F). Notopodia with abundant brachial filaments ( Fig. 14F), dorsally and laterally, each filament swollen, appearing septate, tips bifurcate. Dorsal cirri thin, long, slightly clavate, tips filiform. Cirrophores bulbous basally, elongate; elytrophores wide with large elytral scars. Ventral cirri short, not reaching neuropodial tips. Nephridial papillae thick, long.   FIGURE 14.  Chaetacanthus pilosus( Treadwell, 1937), holotype (AMNH 3531). A. Anterior end, dorsal view. B. First elytron, dorsal view. C. Elytron from second pair, dorsal view. D. Elytron from posterior segment, dorsal view. E. Parapodium from median segment (arrow points to branchiae), anterior view. F. Parapodium from another median segment (arrow points to branchiae). Scale bars: A: 2.4 mm; B–D: 1.1 mm; E, F: 0.4 mm.   FIGURE 15.  Chaetacanthus pilosus( Treadwell, 1937), holotype of  Lepidonotus pomarae panamensis Hartman, 1939a(LACM 39). A. First elytron, dorsal view. B. Same, pedunculated macrotubercles. C. Elytron from posterior segment, dorsal view. D. Same, pedunculated macrotubercles, distally hemispherical. Scale bars: A, C: 1.1 mm; B, D: 0.6 mm. Notochaetae abundant, thin, spinous capillaries, thinner and shorter than neurochaetae ( Fig. 14E, F). Neurochaetae thick, dark amber ( Fig. 14F), upper fascicle with shorter chaetae with long entire tips, lower ones curved, subdistally with short spines.   Remarks. Although Hartman (1939a)did not examine the typematerial of  L. pilosus,she correctly regarded it as belonging to Chaetacantusbut as a junior synonym of  C. magnificus( Grube, 1876). Typematerial of both species was examined. Treadwell (1937)described and illustrated the typeof  L. pilosusindicating it has parapodial branchial filaments, and this confirms its belonging into  Chaetacanthus.However,  C. pilosusdiffers from  C. magnificus( Grube, 1876), herein synonymized with  C. brasiliensis( de Quatrefages, 1866). The main difference is that the elytra of  C. pilosusdo not have the prominent patch of sclerotized, amber macrotubercles arranged in honeycomb like patches, because of this difference  C. pilosusis redescribed. The nominal species,  Lepidonotus pomareae, and the subspecies, L. p. panamensis, both have branchial filaments between successive parapodia ( Fig. 16F). However, because the features of  L. pomarae panamensisare the same as those shown by  C. pilosusin prostomium ( Fig. 16A), elytral ornamentation ( Figs 15A–D; 16B–E), notochaetae and neurochaetae ( Fig. 16G, H), the subspecies deserved to be raised in status as a full species, as correctly indicated by Hartman (1948)as  C. panamensis(Hartman, 1939). Nevertheless, this species shares the same morphological pattern with  C. pilosus( Treadwell, 1937)and it is herein regarded as a junior synonym of the latter. Furthermore, it is interesting to note that in the USNM in Washington(USNM 47981), there is another specimen incorrectly labeled as the holotypeof  Lepidonotus panamensisHartman, 1939, collected in Honda Bay, near Coiba Island (R/V Velero III, Sta. 861-38). Hartman (1939: 44) included three specimens for her  Lepidonotus pomareae panamensis, two from Station 863-38, and one from station 254-34, with no specimen from any other locality (station 861-38). Consequently, that additional USNM specimen cannot be the holotype(ICZN 1999, Art. 73.1). It must be indicated that in  C. pomareae( Kinberg, 1856), elytra of median segments only have bulbous microtubercles with thick tips, whereas in posterior elytra the prominent conical macrotubercles are basally spinous with long, smooth tips (see below), and these macrotubercles are not present in  C. pilosus.     Typelocality.Arena Bank ( 23°29’ N, 109°24’ W), Gulfof California.   Distribution.Gulf of California and Bahía Honda, Panama. 2989844304 1936-04-20 AMNH 23.483334 Arena Bank 1255 -109.4 Gulf of California 16 411 AMNH 3531 1 holotype 2989844316 1938-03-01 LACM North Island, R & V Velero Panama 64 Bahia Honda North Island 16 411 LACM 3 1 holotype 2989844309 1939-01-26 LACM V Velero & Sta. Panama Bahia Honda 72 7.759722 Eastern Pacific 21 -81.593056 One 16 411 LACM 863-38 2 holotype 2989844313 [199,981,402,429] 23.483334 Gulf 1255 -109.4 19 414 1 California holotype