Hypoplectrus espinosai, Puebla & Aguilar-Perera & Helmkampf & Robertson & Estapé & Estapé & Domínguez-Domínguez, 2025

Puebla, Oscar, Aguilar-Perera, Alfonso, Helmkampf, Martin, Robertson, D. Ross, Estapé, Carlos J., Estapé, Allison Morgan & Domínguez-Domínguez, Omar, 2025, Hypoplectrus espinosai sp. nov. (Teleostei: Serranidae), a new hamlet on coral reefs in the southwestern Gulf of Mexico, Zootaxa 5618 (4), pp. 509-524 : 514-519

Hypoplectrus espinosai sp. nov. Puebla, Aguilar-Perera, Robertson & Domínguez-Domínguez 2025

Zoobank LSID: urn:lsid:zoobank.org:act:975A80C9-4CA7-4C91-B8B6-506054C3CA66

English common name: Campeche Bank hamlet

Spanish common names: mero del Banco de Campeche (AFS), vaca del Banco de Campeche (FAO), hamlet del Banco de Campeche (vernacular)

Figure 4 ; Table 1

Holotype. UMSNH CPUM 14398 (specimen) and CTUM 62555 (tissue sample), 90.4 mm SL, Cayo Arcas , Campeche Bank, Campeche, Mexico (20°12′14″N, 91°58′15″W), 24 June 2018, reef, pole spear. Omar Domínguez-Domínguez, Xavier Madrigal Guridi, D. Ross Robertson, David Tafolla Venegas and Georgina Palacios Morales (European Nucleotide Archive accession number ERS20924495).

Paratypes. UMSNH CPUM 14404 (specimen) and CTUM 62571 (tissue sample), 97.6 mm SL, Cayo Arcas , Campeche Bank, Campeche, Mexico, 25 June 2018, reef, pole spear. Omar Domínguez-Domínguez, Xavier Madrigal Guridi, D. Ross Robertson, David Tafolla Venegas and Georgina Palacios Morales (European Nucleotide Archive accession number ERS20924502) . UMSNH CPUM 14408 (specimen) and CTUM 62585 (tissue sample), 82.2 mm SL, Cayo Arcas , Campeche Bank, Campeche, Mexico (20°11′44″N, 91°57′34″W), 25 June 2018, reef, pole spear. Omar Domínguez-Domínguez, Xavier Madrigal Guridi, D. Ross Robertson, David Tafolla Venegas and Georgina Palacios Morales (European Nucleotide Archive accession number ERS20924506) .

Diagnosis. Hypoplectrus espinosai sp. nov. is distinguished from all named congeners by coloration. Body white with thin vertical lines but no bars (or very faint). Black spot on snout surrounded by electric blue lines. Caudal peduncle entirely covered by black saddle blotch, which extends over posterior part of body, and sometimes over posterior part of dorsal fin. Black saddle blotch is more extensive than in H. unicolor . Black eye-mask characteristic of H. castroaguirrei absent.

Description. The morphometric measurements and meristic counts of the holotype and paratypes are presented in Table 1 . Dorsal X, 15; anal III, 7; pelvic I, 5; pectoral rays 13; mouth terminal. Morphometrics as percentage SL (mean, min–max): body depth 44.2% SL (42.3–45.6); body compressed, width 14.0 (12.5–16.2); head length 40.0 (39.2–41.1); snout length 12.2 (10.4–14.9); orbit diameter 8.9 (8.6–9.2); interorbital width 7.1 (6.8–7.3); upper-jaw length 17.2 (16.7–17.5); caudal-peduncle depth 12.8 (12.3–13.3); caudal-peduncle length 11.1 (8.5–12.7); predorsal length 43.2 (41.8–44.6); prepelvic length 41.8 (40.2–45.0); prepectoral length 39.6 (37.8–41.8); base of dorsal fin 54.7 (53.7–56.6); base of anal fin 20.3 (19.5–21.4); longest dorsal spine 14.9 (13.6–16.0); longest anal spine 13.5 (13.4–13.6); longest anal ray 17.4 (17.4–17.5); caudal-fin length 24.3 (23.4–24.9); pectoral fin length 31.6 (30.9–32.9); pelvic fin length 26.0 (25.2–27.4). Morphometrics as percentage HL (mean, min–max): snout length 30.3 (26.2–36.2); upper-jaw length 43.1 (42.3–44.5); interorbital width (17.7, 17.3–18.2); orbit diameter (22.3, 21.0–23.2). Body moderately deep, caudal fin truncate, pelvic fins elongate ovals with rounded tips.

Live coloration ( Fig. 4 ). The body color ranges from white to pale grayish-white to pale brownish-white with ~15 thin vertical whitish to pale bluish-white lines that extend from the top of the body profile to near the bottom. The face is also white with thin vertical lines, but with a yellowish tint, particularly towards the anterior part (including the jaw). An eye-sized black spot is present on the snout. It is surrounded by electric blue lines that extend onto the forehead, around the eye, and onto the lower jaw and towards the rear corner of the opercle. The caudal peduncle is entirely covered by a black blotch, which extends over the posterior part of the body, and sometimes over the posterior edge of the dorsal fin. The pelvic and anal fins are yellow with a faint bluish tint on the leading edge. The pectoral and caudal fins are translucent. The dorsal fin is translucent, with irregular yellow markings.

Preserved coloration ( Fig. S2 ). Light brown with an eye-sized black spot on the snout and a black saddle blotch covering the caudal peduncle and extending into the posterior part of the body.

Comparisons. Hypoplectrus espinosai sp. nov. is distinguished from its congeners by coloration. The most similarly colored hamlets are H. unicolor and H. castroaguirrei , which differ from H. espinosai sp. nov. most noticeably by a much less extensive caudal-peduncle black saddle blotch in both species and the presence of a strong black eye-mask in H. castroaguirrei . The range of morphometric measurements and meristic counts of the H. espinosai sp. nov. holotype and paratypes largely overlap with congeners. Hypoplectrus espinosai sp. nov. has body and fin shapes and sizes similar to the majority of its congeners, except for H. gemma , which also occurs in Campeche Bank and has a semilunate caudal fin, and an undescribed black-colored hamlet from the northeastern Caribbean that also has a semilunate caudal fin as well as pointed pelvic fins. The thin vertical lines on the body and face can also be present in H. unicolor ( Fig. 1f ) and H. castroaguirrei ( Fig. 2 b ), but they are more pronounced and consistently present in H. espinosai sp. nov.

Etymology. We assign the species name espinosai sp. nov. in honor of Héctor Salvador Espinosa Pérez (1954– 2022), a dedicated Mexican ichthyologist, founder of the Mexican Ichthyological Society and curator of the Mexican National Fish Collection. The common name refers to the geographic distribution of the species, the Campeche Bank off the north coast of the Yucatan Peninsula in the southwestern Gulf of Mexico, Mexico.

Behavior. Like its congeneric species, Hypoplectrus espinosai sp. nov. is diurnal and solitary. It was not observed displaying aggressive mimicry behavior as H. unicolor does in Panama ( Puebla et al. 2007, 2018).

Ecology. Hypoplectrus espinosai sp. nov. is mostly associated with shallow coral-reef habitats at depth ranges between 1 m and 20 m. Maximum known size is 97.6 mm TL.

Geographic distribution. Hypoplectrus espinosai sp. nov. is distributed throughout coral reefs from the Campeche Bank in the southern Gulf of Mexico ( Mexico), including coral reefs in the Alacranes Reef, Triángulo Este, Triángulo Oeste, Cayo Arenas, and Cayo Arcas. It has not been recorded far outside of the Campeche Bank, implying that it is likely endemic to this geographic area.

Figures

FIGURE 1. Phenotypic variation in the butter hamlet (Hypoplectrus unicolor). Note the variability in the extent of the black saddle blotch on the caudal peduncle, the presence or absence of this saddle and the snout spot, the occurrence of thin vertical lines (f), and faint vertical bars (e) on the body. a. Roatan, b. Florida Keys, c. Bonaire, d. and e. St. John (USVI), f. Bocas del Toro (Panama). Photographs by Carlos and Allison Estapé.

FIGURE 2. Phenotypic variation in the Veracruz hamlet (Hypoplectrus castroaguirrei). Note the variability in the extent of the black saddle blotch on the caudal peduncle, the presence or absence of the snout spot and a small spot at the base of the pectoral fin, the occurrence of thin vertical lines (b), and faint vertical bars (c) on the body. a. All photographs from Veracruz by Carlos and Allison Estapé.

FIGURE 4. Phenotypic variation of Hypoplectrus espinosai sp. nov. A black saddle blotch covers the caudal peduncle and extends over the posterior part of the body, sometimes over the posterior border of the dorsal fin. Note the consistency of the thin vertical lines. Photographs from Alacranes reef by Carlos and Allison Estapé (a, b, c, d), Isai Dominguez Guerrero (e), and Alfonso Aguilar-Perera (f).