Intertidal chitons (Mollusca: Polyplacophora) from the rocky coastline of Guerrero, México, with the description of a new species Author Reyes-Gómez, Adriana Author Flores-Garza, Rafael Author Galeana-Rebolledo, Lizeth Author Hernández-Vera, Gerardo Universidad de Guadalajara, Centro Universitario de Ciencias Biológicas y Agropecuarias, Departamento de Botánica y Zoología, Carretera a Nogales km. 15.5, Las Agujas Nextipac, Zapopan, Jalisco, C. P. 45110 México. Author Galván-Villa, Cristian M. Author Torreblanca-Ramírez, Carmina Author Flores-Rodríguez, Pedro Author García-Ibañez, Sergio Author Ríos-Jara, Eduardo text Zootaxa 2022 2022-06-23 5155 4 451 492 journal article 80415 10.11646/zootaxa.5155.4.1 2e18793c-3344-4542-92f3-1775f6276bb7 1175-5326 6691172 E6179D38-97E8-4EAB-8F28-8CF6E508C090 Ischnochiton muscarius ( Reeve, 1847 ) Figures 2C–F , 5E–K , 6A–I Distribution. Isla El Venado, Sonora to La Ventosa, Oaxaca, including Isla Socorro, Revillagigedo, México ( Kaas & Van Belle 1990 ). Type specimens. Unascertained, according to Kaas & Van Belle (1990) and Ferreira (1983b) . Type Locality. Unknown , maybe Lower California (according to Kaas & Van Belle 1990 ) . Material examined . 169 specimens , maximum size of 30.4 mm long, 15.5 mm wide. L (n=15); B (n=17); G (n=10); H (n=9); D (n=8); M (n=16); K (n=11); P (n=10); U (n=9); Q (n=12); S (n=6); E (n=5); F (n=11); J (n=7); N (n=5); A (n=10); I (n=8). Habitat. This species is usually found in large aggregations on smooth rocks and with crustose algae. It is particularly abundant in shallow subtidal ( 2–4 m ), buried on small to medium rocks. Juvenile specimens (between 8–16 mm of body length) occur in subtidal to 10 m on small rocks buried in sand. It was collected with C . lurida , T. forbesii and S . limaciformis . Remarks. This species was one of the most abundant species found during this study comprising 26% of the total specimens collected ( Table 2 ). Color varies from olive green, brown, yellow, or gray ( Figs. 2C–F ); frequently the whole tegmentum area of the intermediate valves (IV or V) is dark green or black in color. We also observed dark, fine longitudinal bands in the lateral areas, directed concentrically to the apex; this pattern was also observed in specimens from Nayarit and Mazatlán. However, chitons from southern areas in Oaxaca (e.g., CNMO 5662) lack the characteristic chessboard pattern located on head and tail valve ( Fig. 20K ), as well as the olive-green or dark brown dots on the central areas. TABLE 2. Geographic localization of the collecting sites and description of the wave and substrate type. The code corresponds to the letter assigned to the site in Figure 1 .
Site Code Georeferences Wave exposure Type of substrate
Costa Grande Region
Troncones, La Unión A 17°47' 35.2''N, 101°44' 46.6''W High Blocks, large rocks
Isla Grande, Teniente José Azueta El Capricho Las Gatas, Zihuatanejo Barra de Potosi, Petatlán La Barrita, Petatlán Puerto Vicente Guerrero Ojo de Agua, Tecpan de Galeana Tlacoyunque, Tecpan de Galeana Acapulco Region B C D E F G H I 17°40' 36.8''N, 101°39' 16.7''W 17°38' 12.7″N, 101°33' 05.8″W 17°37' 17.5''N, 101°33' 14.2''W 17°37' 17.5''N, 101°33' 14.2''W 17°24' 32.7''N, 101°10' 51.3''W 17°16' 34.2''N, 101°03' 19.2''W 17°18' 34.8''N, 101°03' 04.9''W 16°19' 35.4''N, 98° 34' 12.6''W Medium Medium Low Low High Medium High High Blocks, large rocks Large and medium rocks Large and medium rocks Rock masses and large rocks Blocks, large and medium rocks Blocks and large rocks Large and medium rocks Blocks, large rocks
Pie de la Cuesta Parque de la Reina J K 16°52' 25.6''N, 99°56' 34.6''W 16°50' 58.2''N, 99°54' 01.8''W High Medium Rock masses and large rocks Large and mediums rocks
.....Continued on the next page TABLE 2. (Continued)
Site Code Georeferences Wave exposure Type of substrate
Muelle Manzanillo Tlacopanocha Palmitas Majahua L M N O P 16°50' 58.2''N, 99°54' 01.8''W 16°50' 27.9''N, 99°54' 38.1''W 16°50' 41.5''N, 99°54' 25.2''W 16°50' 58.2''N, 99°54' 24.1''W 16°50' 58.2"N, 99°54' 20.8"W Medium High Medium Medium High Blocks, large rocks Large and mediums rocks Large to small rocks Large and mediums rocks Large to small rocks
Costa Chica Region
Playa Ventura Casa de Piedra, Copala Las Salinas Peñitas, Marquelia Punta Maldonado, Cuajinicuilapa Q R S T U 16°32' 8.3"N, 99°54' 44.6"W 16º32' 9.8"N, 98º 53' 47.3''W 16°35' 49.5''N, 99°52'43.7''W 16°33' 14.4''N, 98°46'22.0''W 16°19' 35.4''N, 98°34'12.6''W High High High High Medium Rock masses Rock masses and large rocks Rock masses Rock masses Rock masses
TABLE 3. Local distribution of chiton species, the site is indicated by its code (from A–U, see Table 2). It gives the voucher number, the total number of individuals obtained per species and the maximum body size recorded. The site marked in bold, represent the locality in which the maximum body size was registered.
Species Museum catalog number per site No. spp. Max. size (mm) Length Wide
C. lurida N (CNMO5176, CNMO5305), D (CNMO5178, CNMO5276, CNMO5266), T (CNMO5177), U (CNMO5193, CNMO5217), M (CNMO5194, CNMO5220,
CNMO5240), L (CNMO5195, CNMO5204, CNMO5201, CNMO5232 ) , P (CNMO5225, CNMO5229), K (CNMO5246, CNMO5248, CNMO5280), A (CNMO5323), B (CNMO5257), R (CNMO5274), E (CNMO5281, CNMO5330), H (CNMO5283, CNMO5294), G (CNMO5287), F (CNMO5290, CNMO5297), J (CNMO5319), I (CNMO5822). 607 30.9 18.2
C. hanselmani M (CNMO5187), K (CNMO5197, CNMO5213), P (CNMO5227), D (CNMO5247), U (CNMO5269), H (CNMO5296), I (CNMO5324), N (CNMO5408) , A (UAGRO0010). 77 11.8 7.0
I. muscarius L (CNMO5202), B (CNMO5180, CNMO5299), G (CNMO5181, CNMO5300),
H (CNMO5182), D (CNMO5183), M (CNMO5206, CNMO5222), K (CNMO5207), P (CNMO5231), U (CNMO5262), Q (CNMO5272), S (CNMO5276), E (CNMO5289, CNMO5338), F (CNMO5315) , J (CNMO5316), N (CNMO5318), A (CNMO5327), I (CNMO5335). 2194 30.4 15.4
C. elenensis L (CNMO5199), D (CNMO5261), M (CNMO5304, CNMO6064), N (CNMO5311), A (CNMO5325) , K (CNMO5820), F (CNMO5821, CNMO5823). 57 14.8 9.1
C. retusa K (CNMO5185), N (CNMO5189) , H (CNMO5205, CNMO5301), Q
(CNMO5212), M (CNMO5230), P (CNMO5241), U (CNMO5243), D (CNMO5244), F (CNMO5302), I (CNMO5322), E (CNMO5331), A (CNMO5333), S (UAGRO0017), L (UAGRO0018), E (UAGRO0019). 186 24.0 11.9
S. limaciformis K (CNMO5179), L (CNMO5188, CNMO5830), M (CNMO5211, CNMO6070),
N (CNMO5208, CNMO5310), D (CNMO5254), B (CNMO5265, UAGRO0024), F (CNMO5303), A (CNMO5334), U (UAGRO0020), J (UAGRO0021) , G (UAGRO0022), H (UAGRO0023). 258 33.5 11.2
......Continued on the next page TABLE 3. (Continued)
Species Museum catalog number per site No. spp. Max. size (mm) Length Wide
C. albolineatus L (CNMO5203, CNMO5184), U (CNMO5526, CNMO5270), M (CNMO5219, CNMO5221), P (CNMO5233, UAGRO0029), B (CNMO5235), K (CNMO5258),
Q (CNMO5260), U (CNMO5270), D (CNMO5273), H (CNMO5279) , E (CNMO5286, CNMO5329), G (CNMO5292), F (CNMO5298), C (CNMO5306), N (CNMO5320), I (CNMO5337), S (UAGRO0028), J (UAGRO0030), A (UAGRO0031). 2175 40.6 22.4
C. articulatus N (CNMO5200), K (CNMO5209), R (CNMO5216), T (CNMO5218), P (CNMO5237), M (CNMO5242, CNMO5249), C (CNMO5250), B (CNMO5253), D (CNMO5226), U (CNMO5275),
S (CNMO5277), H (CNMO5288), E (CNMO5291, CNMO5326), L (CNMO5393, UAGRO0032), N (CNMO5307), J (CNMO5313), I (CNMO5336) , Q (UAGRO0032), F (UAGRO0034), A (UAGRO0035). 2444 65.9 32.8
T. forbesii M (CNMO5192, CNMO5224, UAGRO0038), K (CNMO5210), P (CNMO5226),
L (CNMO5228), B (CNMO5255), D (CNMO5263), N (CNMO5309) , I (CNMO5328), U (UAGRO0037). 68 40.5 23.0
A. arragonites G (CNMO5196), P (CNMO5223), R (CNMO5251), A (CNMO5264), S
(CNMO5267), U (CNMO5268), F (CNMO5282), E (CNMO5295), N (CNMO5308), J (CNMO5312), I (CNMO5474) , A (UAGRO0039). 43 9.9 5.8
L. salvadorensis R (CNMO5186), B (CNMO5245), U (CNMO5252), S (CNMO5259), F
(CNMO5284), I (CNMO5321), E (CNMO5332), K (UAGRO0040) , N (UAGRO0041), P (UAGRO0042), M (UAGRO0043). 23 11.2 5.9
L. acapulcoensis S (CNMO5234, CNMO5271, CNMO5782, CNMO5792), P (CNMO5236), I (CNMO5779), N (CNMO5781, CNMO5784, CNMO6061), Q (CNMO5785), J (CNMO5793, CNMO5794), U (CNMO5795), C (CNMO6069), M (UAGRO0045) , R (UAGRO0046), H (UAGRO0047), E (UAGRO0048), D (CNMO0049), A (UAGRO0049), F (UAGRO0071). 76 12.2 5.8
TABLE 4. Barcode sequence data of the analyzed species, voucher number and GenBank accession. Bold names indicate the species sequenced in this study.
Taxa coxl
Lepidochitona bullocki KJ872762 KJ872763
Lepidochitona liozonis KJ872769 KJ872764
Lepidochitona pseudoliozonis KJ872765 KJ872767
Lepidochitona beanii * MZ821770
Lepidochitona acapulcoensis sp. nov. Lepidochitona salvadorensis * MW279215 * MZ821768 * MW279216 * MZ821769 * MW279217 *MZ541987
Lepidochitona aleutica (OG) KC776924
Chiton albolineatus (OG) * MZ073998
FIGURE 2. Dorsal view of the whole specimens that represent the analyzed species. A, Chaetopleura lurida , BL 27.48 x 15.70 mm, Majahua, Acapulco (CNMO 5229). B, Chaetopleura hanselmani , BL 11.02 x 7.16 mm, Tlacopanocha, Acapulco (CNMO 5804). Ischnochiton muscarius , C, BL 16.62 x 9.77 mm, Angosta, Acapulco (CNMO 5202); D, BL 15.12 x 9.55 mm, Barra de Potosí Protegida, Petatlán (CNMO 5338); E, BL 18.30 x 10.17 mm, Troncones, La Unión (CNMO 5327); F, BL 14.98 x 9.51 mm, La Barrita, Petatlán (CNMO 5315). G, Callistochiton elenensis , BL 12.32 x 7.76 mm, La Barrita, Petatlán (CNMO 5823). H, Callistoplax retusa , BL 20.41 x 9.68 mm, Parque de la Reina, Acapulco (CNMO 5185). Stenoplax limaciformis , I, BL 17.56 x 7.21 mm, Parque de la Reina, Acapulco (CNMO 5179); J, BL 20.12 x 9.15 mm, Tlacopanocha, Acapulco (CNMO 5208); K, BL 17.65 x 8.29 mm, Las Gatas, Zihuatanejo de Azueta (CNMO 5254); L, BL 19.78 x 9.84 mm, Isla Grande, Zihuatanejo de Azueta (UAGRO 0024). Chiton albolineatus , M, BL 23.84 x 14.63 mm, Piedra de Tlacoyunque, Tecpan de Galeana (CNMO 5337). Tonicia forbesii , BL 33.41 x 17.86 mm, Isla Grande, Zihuatanejo de Azueta (CNMO 5255). Acanthochitona arragonites , O, BL 8.80 x 5.2 mm, Las Salinas, Copala (CNMO 5267). Lepidochitona salvadorensis , P, BL 10.63 x 5.7 mm, Barra de Potosi Protegida, Zihuatanejo de Azueta (CNMO 5332). FIGURE 3. Chaetopleura lurida , disarticulated valves of a specimen BL 20.31; valves in dorsal view A, head valve; B, intermediate valve IV; C, tail valve. Valves in ventral view, D, head valve; E, intermediate valve IV; F, tail valve. SEM images of a specimen BL 15.9 mm length. Valves in dorsal view; G, head valve; H, intermediate valve IV, I, tail valve. J, intermediate valve IV in ventral view. FIGURE 4. Chaetopleura lurida , SEM images of a specimen BL 15.9 mm, A, girdle corneous hairs; B, girdle spicules; C, radular teeth. Chaetopleura hanselmani , BL 10.11 mm; valves in dorsal view, D, head valve; E, intermediate valve IV. Valves in ventral view, F, head valve; G, intermediate valve IV. SEM images of a specimen BL 10.9 mm; valves in dorsal view, H, head valve; I, intermediate valve IV; K, tail valve. J, valve IV in ventral view. FIGURE 5. Chaetopleura hanselmani , SEM images of a specimen BL 10.9 mm; A, girdle spicules; B, detail of spicules ornamentation; C, radular teeth; D, detail of central and minor lateral teeth. Ischnochiton muscarius , disarticulated valves of a specimen BL 22.31 x 11.95 mm, Las Gatas, Zihuatanejo de Azueta, (CNMO 5183). Dorsal view of valves, E, head valve; F, intermediate valve IV; G, tail valve. Ventral view of valves, H, head valve; I, intermediate valve IV; J, tail valve. K, detail of girdle scales. FIGURE 6. Ischnochiton muscarius , SEM images of a specimen BL 13.1 mm; valves in dorsal view, A, head valve; B, intermediate valve IV and in ventral view, C, detail or articulamentum of valve IV; D, tail valve in dorsal view. E, aesthete system detail of intermediate valve IV; F, girdle scales; G, detail of girdle scales surface; H, radular teeth; I, detail of major lateral teeth. Callistochiton elenensis , disarticulated valves of a specimen BL 11.09 mm, Manzanillo, Acapulco (CNMO 5304); dorsal view of valves, J, head valve; K, intermediate valve IV. Family Callistoplacidae Pilsbry, 1893