Caecidotea villalobosi, García-Vázquez & Pedraza-Lara & Rodríguez-Almaraz, 2021

García-Vázquez, Leonardo, Pedraza-Lara, Carlos & Rodríguez-Almaraz, Gabino, 2021, Six new epigean species of Caecidotea (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico, Zootaxa 4965 (1), pp. 45-77 : 67-70

Caecidotea villalobosi sp. nov.

( Figs 18–21 )

Material examined: Holotype, male ( CNCR 35506 ), length 11 mm; Lago de Catemaco , Coyame, 18°26’12”N, 95°01’27”W, elev. 359 m, Municipality Catemaco, Veracruz, Mexico, 2 November 2017, coll. L. García-Vázquez and C. Pedraza-Lara.

Paratypes, male ( CNCR 35507 ), length 10.0 mm; same data of collection and collectors as holotype; dissected parts pereiopod I, pereiopod IV, pleopod II; dissected structures for right pleopod drawings I, III, IV and V in the specimen tube. 2 males and 3 females ( CNCR 35508 , CNCR 35509 ), Laguna Mahahual, 18°39’36”N, 95°18’30W, Municipality San Andrés Tuxtla, Veracruz, Mexico, coll. J. L. Villalobos, E. Moreno and I. Toledano.

Diagnosis. Male body 3.2 times longer than wide. Head width 1.4 length, anterior margin concave, lateral margins straight; eyes width 2.1 length, postmandibular lobes not produced; Pereiopod I with dactylus inner edge serrated; dactylus pereiopod IV serrated.

Description. Male (CNCR 35506) 11 mm ( Fig. 18A ); head trapezoidal, head width 1.4 length, anterior margin concave. Eyes present, oval, dark pigmented, width 2.1 length. Postmandibular lobes not produced. Subrectangular pereionites, lateral margins with setae.

Pereionite 1 length 0.9 pereionite 2 length; pereionite 1 1.1 pereionite 3 length; pereionites 6–7 with oval margins; posterior widening.

Antennula flagellum with 9 articles, longer than distal antenna podomere middle; last four segments with aestetascs with formula 1–0–1–0. Antenna flagellum with 57 articles with pectinate setae; proximal article longer than wide; following articles decreasing in length.

Pereiopod I ( Figs 18B , 19A–B ) dactylus with robust seta on dactylus, inner edge serrated; proximal process with 3 robust setae; acute mesial process not exceeding dactylus width, bicuspid distal process. Pereiopods II– III ( Figs 18C–D ) similar length. Pereiopod IV ( Figs 18E , 19C–D ), propodus with robust finger-like projection in dactylus, dactylus length 0.9 propodus length, dactylus serrated. Pereiopod V ( Fig. 18F ) length basis 1.4 propodus length, dactylus curved hooked. Pereiopod VI ( Fig. 18G ) smaller than pereiopod VII, basis length 1.3 propodus length, dactylus with spine on lower margin. Pereiopod VII ( Fig. 18H ) length 0.4 body length.

Pleopod I ( Fig. 20A ) length 1.1 pleopod II length; basal segment oval, proximal margin straight, length 1.3 width, internal margin with 3 retinacula, distal segment oval, outer margin curved in apical portion, length 1.8 width, margins with 12 simple setae.

Pleopod II ( Fig. 21A–F ), protopod subsquare, inner proximal edge straight, with simple short distal seta, dorsal distal edge with cuticular scales; exopod base with spine on right distal border, exopod oval, with rows cuticular scales, distal margin with 15–19 long plumose setae; slender endopod, as long as 3.5 width, exopod length 0.7 protopod length; inner surface curved; internal and external processes prominent, apex with 3 terminal processes: caudal process rounded, cannula short subcylindrical, with a circular apex; mesial process present; endopod subapical portion armed with 14–16 cuticular scales.

Pleopod III ( Fig. 20B ), exopod oval with distal margin setose, length 1.2 endopod length, width 1.9 endopod width, transverse suture in proximal half, 21 marginal plumose setae, external margin with 8 simple setae; endopod oval, 1.2 exopod length.

Pleopod IV ( Fig. 20C ), exopod length 1.5 width, external margin with 4 proximal setae, endopod length 1.1 exopod length.

Pleopod V ( Fig. 20D ), exopod oval, exopod length 1.9 width; external margin with 4 simple setae; transverse suture not evident; endopod notched on outer proximal edge, endopod width 1.2 exopod width.

Pleotelson ( Fig. 20E ), subsquare, width 1.1 length, lateral margins parallel, with simple setae, caudomedial lobe produced subacute.

Uropods ( Fig. 20F ), length 0.7 pleotelson length, armed with robust setae; endopod and exopod lanceolate, endopod length 1.0 exopod length, exopod length 1.1 protopod length.

Habitat. The Caecidotea villalobosi sp. nov. specimens were collected on the shore of Catemaco Lake, below rocks submerged in water, as well as on the roots of the water lily Eichornia crassipes . It is important to mention that this species is not abundant in the region.

Distribution. Known from the type locality and Laguna Mahahual, San Andrés Tuxtla, Veracruz.

Etymology. This species is named after Dr. José Luis Villalobos Hiriart for being an exemplary mentor for the first author and for being an exceptional carcinologist, as well as his contributions to the knowledge of Mexican crustaceans.

Remarks. Argano (1977) reported C. communis ( Say, 1818) in the Catemaco lake in similar conditions where we collected Caecidotea villalobosi sp. nov., between the roots of a water lily and under submerged rocks on the shore of the lake. Argano mentioned that C. communis has a wide distribution in Mexico and also takes up Bowman’s (1975) hypothesis about an artificial introduction to Mexico due to human action. However, morphological comparisons with the species C. communis sensu Williams (1970) , allow it to be clearly distinguished by the following characters: rounded head, anterior margin concave; pleotelson in C. communis is subcircular, as long as wide; caudomedial lobe obtuse produced; pleopod I wider and subrectangular, with 24 simple setae in distal margin, while Caecidotea villalobosi sp. nov. has 12 simple setae. The number of retinacula is 5 in C. communis while Caecidotea villalobosi sp. nov. has 3 retinacula; Regarding the apical elements of the pleopod II endopod, the cannula of C. communis is thin, simple, and elongated, surpassing the distal edge of the caudal process, which lacks cuticular scales. The cannula of Caecidotea villalobosi sp. nov. is short, subcylindrical, does not reach the distal edge of the caudal process and has cuticular scales.

Figures

FIGURE 18. Caecidotea villalobosi sp. nov. Holotype male (CNCR 35506), total length 11 mm, A, male habitus. Paratype male (CNCR 35507) total length 10 mm, B, pereiopod I; C, pereiopod II; D, pereiopod III; E, pereiopod IV; F, pereiopod V; G, pereiopod VI; H, pereiopod VII. Scale bars: A = 2.0 mm, B–H = 1.0 mm.

FIGURE 19. Caecidotea villalobosi sp. nov. Paratype male (CNCR 35507), total length 10 mm, A, right pereiopod I ventral view; B, right pereiopod I dorsal view; C, right pereiopod IV ventral view; D, right pereiopod IV dorsal view. Scale bars A–D = 500 µm.

FIGURE 20. Caecidotea villalobosi sp. nov. Paratype male (CNCR 35507) total length 10 mm, A, pleopod I; B, pleopod III; C, pleopod IV; D, pleopod V; E, pleotelson and uropods. Scale bars: A–E = 1.0 mm.

FIGURE 21. Caecidotea villalobosi sp. nov. Paratype male (CNCR 35507), total length 10 mm, A, pleopod II ventral view; B, pleopod II dorsal view; C, endopod pleopod II dorsal ventral view; D, endopod pleopod II ventral view; E, apex of the endopod pleopod II ventral view; F, apex endopod pleopod II dorsal view. Scale bars: A–B = 400 µm, C–D = 100 µm, E = 40 µm, F = 30 µm.