Caecidotea buzwilsoni, 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 : 53-56

Caecidotea buzwilsoni sp. nov.

( Figs 6–9 )

Material examined: Holotype male ( CNCR 35528 ), length 8.0 mm, Laguna de Yuriria , 20°13’11”N, 101°11’05”W, elev. 2275 m, Municipality Yuriria, Guanajuato, Mexico, 22 October 2019, coll. L. García-Vázquez and C. Pedraza-Lara.

Paratypes, male ( CNCR 35529 ), length 7.6 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. 15 Males and 10 females ( CNCR 35530 ) .

Diagnosis. Male body length 3.2 width. Head trapezoidal, width 1.9 length, anterior margin straight; eyes large oval, length 2.0 width. Pleopod IV exopod suture transverse complete. Uropod endopod elongated, oval, length 2.2 width; exopod lanceolate, slender, length 2.7 width.

Description. Male (CNCR 35528) 8.0 mm ( Fig. 6A ); head width 1.9 length, anterior margin concave. Eyes present, oval, dark pigmented, length 2.0 width. Postmandibular lobes not produced. Subrectangular pereionites, ornamented with marginal setae.

Pereionite 1 length 1.2 pereionite 2 length; pereionites 6–7 wider, with diagonal margins, widening in posterior angle.

Antennula flagellum with 11 articles, longer than distal antenna podomere middle; last four segments with aestetascs in formula 1–1–1–1. Antenna flagellum with 67 articles; proximal article wider than long; following articles increasing in length.

Pereiopod I ( Figs 6B , 7A ), triangular propodus, dactylus curved, propodus palm longer than dactylus; palm with inner and outer edges, ornamented with simple setae; proximal process with 3 robust setae; mesial process acute, not exceeding dactylus width; distal process Subacute length 0.3 mesial process length. Pereiopods II–III ( Figs 6C–D ), with similar length. Pereiopod IV ( Figs 6E , 7B–C ), propodus with spine in dactylus; dactylus length 0.6 propodus length, with four spines on lower margin. Pereiopod V ( Fig. 6F ), basis length 1.3 propodus length. Pereiopod VI ( Fig. 6G ), similar length to pereiopod VII, basis length 1.2 propodus length. Pereiopod VII ( Fig. 6H ), length 0.7 body length.

Pleopod I ( Fig. 8A ) length 2.3 pleopod III length; protopod oval, proximal margin straight; protopod 1.7 width, inner margin with 5 retinacula, distal segment subrectangular, outer margin medially straight, length 2.0 width, margins with 23 simple setae.

Pleopod II ( Fig. 9A–F ), protopod subsquare, proximal edge rounded; in dorsal view, exopod base with one distal spine on inner edge, exopod oval with small cuticular scales directed distally on inner dorsal margin, exopod distal margin with 21 plumose setae; slender endopod, with pubescent surface, mesial portion curved, length 3.5 width, similar length to exopod 0.6 protopod length, internal and external process prominent, external with suture close to base, endopod apex with 3 processes: cannula conical, short, with truncated apex lower than caudal process, extending proximally from cannula more than 3.0 its length; mesial process evident; caudal process robust, conical, rounded apex, armed on subapical dorsal surface with 1–17 cuticular scales directed proximally; cuticular scales with pubescence, similar to short villi.

Pleopod III ( Fig. 8B ), exopod oval with distal margin setose, length 1.2 endopod length, width 1.8 endopod width, transverse suture in proximal half, 18 distal plumose setae, external margin 13 simple setae; endopod short oval, length 0.8 exopod length.

Pleopod IV ( Fig. 8C ), exopod oval, as long as 1.9 width, external proximal margin with transverse suture, close to pleopod joint; endopod 0.9 exopod length.

Pleopod V ( Fig. 8D ), exopod oval, length 1.8 width, transverse suture not evident; endopod length 0.9 length, width 0.9 exopod width.

Pleotelson ( Fig. 8E ), subsquare, width 1.2 length, lateral margins parallel, with simple setae, caudomedial lobe broad rounded.

Uropods ( Fig. 8E ), length 0.8 pleotelson length, armed with robust setae; endopod oval, as long as protopod; exopod length 0.9 protopod length.

Habitat. This species was collected between roots of the water lily Eichornia crassipes , which floated in a channel of approximately 2 meters wide by one meter deep.

Distribution. Known only from the type locality.

Etymology. This species is named in honor to Dr. George D. F. Wilson (Buz), Saugatuck Natural History Laboratory, in recognition to his career with the isopods and for being a mentor and for his friendship with the first author.

Remarks. Caecidotea buzwilsoni sp. nov. represents the first record of Caecidotea for the Mexican state of Guanajuato. Its morphology is similar to Caecidotea zacapuensis sp. nov. both species can be differentiated by the transverse suture of pleopod IV, which in Caecidotea zacapuensis sp. nov. is incomplete while in Caecidotea buzwilsoni sp. nov. is complete.

Figures

FIGURE 6. Caecidotea buzwilsoni sp. nov. Holotype male (CNCR 35528), total length 8.0 mm, A, male habitus. Paratype male (CNCR 35529) total length 7.6 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 7. Caecidotea buzwilsoni sp. nov. Paratype male (CNCR 35529), total length 7.6 mm, A, right pereiopod I ventral view; B, pereiopod IV dorsal view; D, right pereiopod IV ventral view. Scale bars: A, C–D = 500 µm, B = 400 µm.

FIGURE 8. Caecidotea buzwilsoni sp. nov. Paratype male (CNCR 35529), total length 7.6 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 9. Caecidotea buzwilsoni sp. nov. Paratype male (CNCR 35529), total length 7.6 mm, A, pleopod II ventral view; B, pleopod II dorsal view; C, endopod pleopod II ventral view; D, endopod pleopod II dorsal view; E, apex of the endopod pleopod II ventral view; F, apex endopod pleopod II dorsal view. Scale bars: A = 400 µm, B = 300 µm, C–D = 100 µm, E = 40 µm, F= 30 µm.