Caecidotea camaxtli (Isopoda: Asellidae) a new species from the Tlaxcala valley, Mexico García-Vázquez, Leonardo Rodríguez-Almaraz, Gabino Pedraza-Lara, Carlos Zootaxa 2019 2019-07-01 4624 3 377 386 8474Z García-Vázquez & Rodríguez-Almaraz & Pedraza-Lara, 2019 García-Vázquez & Rodríguez-Almaraz & Pedraza-Lara 2019 [151,396,937,964] Malacostraca Asellidae Caecidotea Animalia Isopoda 1 378 Arthropoda species camaxtli sp. nov.   Figs 1–5   Material examined.   Holotype, male ( CNCR 35080), body length 13.5 mm,  Laguna El Ojito, San Luis Apizaquito, Municipality of Apizaco, Tlaxcala, Mexico, water channel adjacent to main access road to the reservoir below bridge, 19°26’00’’N, 98°06’00’’W,  2 April 2017, coll. L. García-Vázquez, J. García and S. Martínez.    Paratypes, male ( CNCR 35081; dissected parts of pereopod I, pleopod II and the left genital papillae, CNCR 35084; dissected structures for line drawings of left pleopods I, III, IVand V in the specimen’s tube), body length 13 mm. Female ( CNCR 35082), body length 6.4 mm.  15 malesand 15 females( CNCR 35083).  10 malesand 10 females(FCB-UANL-C440-08177), all with the same data as the holotype.   Diagnosis. Head anterior margin concave, length approximately 2.0 times width; post-mandibular lobes not produced. Pleotelson lateral margins parallel, caudal lobe rounded. Pleopod II exopodite ovate, as long as endopodite; endopodite tip with three processes, caudal process with cuticular scales. Uropod endopodite wide, lanceolate.   Description.Male (CNCR 35080) 13.5 mm( Fig. 1A, B); pleotelson with setae as long as antennular article 1. Head width 2.0 times length, anterior margin concave. Eyes present, pigmented, 1.9 times long as wide. Lateral margins with several setae. Post-mandibular lobes not produced. Pereonites lateral margins subrectangular with several setae of same length that first antennular article on lower and upper edges.  Pereonite 11.5 length pereonite 2–3 length; pereonites 6 and 7 slightly wider; pereonites 4–7 widest, lateral margin subrectangular, narrowing posteriorly. Genital papillaetube-like ventrally on pereonite 7 and pleonite 1 ( Fig. 3F, G) with 1–3 small spines on margin, located in posterior ventral margin of last thoracic segment.  Antennulaflagellum with 10 articles on both sides, reaching distal border of the last segment peduncle antennal when projected forward; penultimate segments with aestetascs in formula 1–0–1–1. Antennaflagellum with 77 articles; proximal article longer than wide; following articles decreasing in length.  Pereopod I( Figs 2A, 3A) dactylus length 1.3 times length of palm, internal border with distinct serration distally before claw; palmar margin with rounded protuberance on joint of dactylus; mesial and distal process with rows of simple setae on both lateral edges. Pereopods II–IIInot dimorphic subequal in lengths ( Fig. 2B, C). Pereopod IV( Fig. 2D) dimorphic, dactylus length near propodus length, dactylus with row of three strong spines. Pereopod V( Fig. 3E) propodus subequal to carpus length. Pereopod VI( Fig. 2F) similar length to pereopod VII, propodus similar length to carpus; merus with subcircular projection on midpoint of external margin. Pereopod VII( Fig. 2G) length 2.9 times body length; merus with carina at midpoint of lower margin.  Pleotelsonwidth 1.2 times length, lateral margins parallel, with several simple setae, caudomedial lobe rounded.   FIGURE 1.  Caecidotea camaxtli  sp. nov.Laguna El Ojito, San Luis Apizaquito, Municipality of Apizaco. A, B. Holotype male (CNCR 35080), 13.5 mm. C, D. paratype female (CNCR 35082) A, habitus; B, right uropod; C, habitus; D, right uropod. Scale bars = 2.5 mm (A), 1.4 mm (B), 1 mm (C, D).   FIGURE 2.  Caecidotea camaxtli  sp. nov.Laguna El Ojito, San Luis Apizaquito, Municipality of Apizaco, paratype male (CNCR 35081), 13 mm, left pereopods A, pereopod I; B, pereopod II; C, pereopod III; D, pereopod IV; E, pereopod V; F, pereopod VI; G, pereopod VII. Scale bars = 1 mm (A–G).  Pleopod Ilength 1.3 times pleopod II length; protopodite subtriangular, proximal margin rounded, length 1.7 times width, internal margin with 4–6 coupling hooks, distal segment subrectangular, external margin concave, length 1.8 width, length subequal to proximal article length, distal margin and lateral margins with 22–25 simple setae ( Fig. 4A).  Pleopod IIprotopodite subcircular, tear-shaped, with 1 robust seta near external distal angle; outer margin of exopodite proximal segment with 4 simple setae; exopodite distal article oval, margin with 17–25 long plumose setae; endopodite slender, length 3.6 times width, medial portion curved, length 1.3 times exopodite length, endopodite length 1.6 times protopodite length, internal and external process prominent, endopodite apex with 3 processes, caudal process with protuberances, cannula reaching half of caudal process with subcylindrical apex ending in acute peak, mesial process evident at base of cannula ( Fig. 3B); endopodite armed with 5–15 cuticular scales ( Fig. 3C, D).  Pleopod IIIexopodite oval with distal margin setose, length 1.4 times endopodite length, width 1.8 times endopodite width, with transverse suture, 23 plumose setae on distal margin, outer margin with 24–26 simple setae; endopodite small oval 1.4 times exopodite length ( Fig. 3B).  Pleopod IVdistal margin exopodite with 10 proximal setae, length 1.6 times width; length 1.2 times endopodite length ( Fig. 4C).  Pleopod Vexopodite subrectangular, length 1.6 times width, transverse suture present; exopodite proximal external margin with 7 simple setae, length 1.4 times endopodite length, width 1.3 times endopodite width; endopodite length 1.6 times width ( Fig. 4D).  Uropodslength subequal to pleotelson length, armed profusely with robust setae; endopodite wide lanceolate, length 0.8 times protopodite length, length 0.7 times exopodite length; exopodite length 2.2 times width; protopodite length 1.5 times width.  Female paratype(CNCR 35082), 6.4 mm( Fig. 1C); pleotelson with several setae length 2.0 eye width. Head width 2.4 times length, anterior margin concave. Eyes 2.4 times wider than long, pigmented. Post-mandibular lobes not produced, with setae as long as eye width. Pereonite3 maximum width 2.1 mm.  Pereoniteslateral margins subrectangular. Pereonite 1length 0.85 times pereonites 2–3 length, wider than the rest. Pereonites 4–7with lateral margins subrectangular, narrowing posteriorly with setae on lower and upper edges, length subequal to eye width.  Antennulaflagellum with 9 articles, extending to base of first antennal article when projected forward; penultimate segments with aestetascs in formula 1–1–0–1. Antennasmissing.  Pereopod Inot as robust as in male; dactylus length subequal to palm length, internal border with distinct strong spines; palm margin with 2 rows robust setae on both lateral edges, without mesial and distal processes. Pereopod IIlonger than pereopod I; dactylus length subequal to propodus length. Pereopods III–VIIwith sub-parallel lateral margins. Pereopod VII2.0 times body length.  Pleotelsonwidth subequal to length, lateral margins sub-parallel, with simple setae; caudomedial lobe round- ed.  Uropodsbiramous, length 2.2 times pleotelson length, with simple setae; endopodite longer than protopodite, length 0.7 times protopodite length, length 0.5 times exopodite length; exopodite length 3.0 times width; protopodite length 1.6 times width ( Fig. 1D).  Habitat.This species was found in small reservoir, which was created by impounding a natural spring. The specimens were associated with the roots of submerged riparian vegetation, including reeds, as well as in the surface and cavities of submerged volcanic rocks within channels that flow out of the reservoir.   Distribution.Only known from the typelocality.   Etymology.This species is named after Camaxtli, the god of war, faith and hunting, who is part of the TlaxcalaValley’s mythology.   Remarks.Among the Mexican epigean species of  Caecidotea, males of  C. camaxtli  sp. nov.have the longest body ( 13 mmin average;  C. puebla: 10.3 mm  C. xochimilca: 10.5 mm,  C. williamsi: 4.4 mm) ( Cole & Minckley 1968; Rocha-Ramírez & Peñaloza-Daniel 2011; Escobar-Briones & Alcocer 2002).  C. camaxtli  sp. nov.can be distinguished from its Mexican epigean congeners by the form of the pereopods, the chaetotaxy of pereopod I, as well as the sinuous edge of the palm, having pleotelson with parallel lateral margins, rounded caudomedial lobe, and by the rounded proximal margin and tear-shape of the protopodite of pleopod II. Additionally, three processes are present on the apex of the endopodite: a long and rounded caudal process with cuticular scales, a mesial process and a short simple cannula.  Caecidotea camaxtli  sp. nov.can be separated from  C. communisby the possession of a tearshape protopodite of pleopod II and by lanceolate and wider uropods which are profusely covered by setae, while  C. communisshows a subsquare protopodite of pleopod II, and narrower uropods with scarce setae covering.   FIGURE 4.  Caecidotea camaxtli  sp. nov.Laguna El Ojito, San Luis Apizaquito, Municipality of Apizaco, paratype male (CNCR 35081), 13 mm, left pleopods. A, Pleopod I; B, Pleopod III; C, Pleopod IV; D, Pleopod V. Scale bars = 0.3 mm (A), 0.5 mm (B–D).   FIGURE 5.  Caecidotea camaxtli  sp. nov.Laguna El Ojito, San Luis Apizaquito, Municipality of Apizaco, holotype male (CNCR 35080), 13.5 mm. A, dorsal view; B, lateral view. Scale bars = 2.5 mm (A, B). Pérez-Rodríguez (1994) reported that Laguna El Ojito was slightly alkaline and morning surface temperature ranged from 14–22°C from January to October. We noted that the sedimentary environments of the lake comprised two main types: 1) lentic waters with clay bottoms, where specimens were found in association with the roots of reeds and 2) lotic waters with terrigenous, sandy or silty clay, where submerged igneous rocks provided hiding places for isopods. Individuals of  C. camaxtli  sp. nov.were abundant in the habitats described above. Other common crustaceans collected concomitantly in Laguna El Ojito included the crayfish C ambarellusm ontezumae(Saussure, 1857) and amphipod  Hyallelasp. Laguna El Ojito currently represents the only known population of  C. camaxtli  sp. nov.and there is uncertainty whether this species is more widely distributed or endemic to this system, which is subject to anthropogenic pressures related to water supply to nearby communities (Pérez-Rodríguez 1994). The discovery of this new species is evidence that freshwater isopod diversity in central Mexicois likely higher than currently recorded. Fleming (1973)and Argano (1977)concluded that  C. communis( typelocality: Pennsylvania, USA) was the only epigean species inhabiting Mexico. However, the description of the new species presented here and  C. puebla,  C. williamsi, and  C. xochimilcasuggest that rather than one species widely ranging from Canadato Mexico,  Caecidoteaspecies in the latter represent a mosaic of endemic/highly localized species ( Fig. 6), and that  C. communis sensu strictomay be not be present in Mexico. Nine species of  Caecidoteahave been recorded from Mexico, five of which are found in surface waters along the Trans-Mexican Volcanic Belt, while the rest inhabits the southwest region, specifically within the karstic basin of Chiapasin caves with subterranean aquatic habitats ( Bowman 1975, Argano 1977). We would expect an increase in the number of species with a greater sampling effort, and analysis of more populations from Mexicocan be carried on. 2273188198 2017-04-02 CNCR Laguna El Ojito & L. Garcia-Vazquez & Garcia-Vazquez, J & S. Martinez. Mexico Municipality of Apizaco 19.433332 Laguna El Ojito 21 -98.1 San Luis Apizaquito 1 378 CNCR 35080 1 Tlaxcala holotype 2273188199 III, IV 1 378 CNCR 35081, CNCR 35084, CNCR 35082 1 paratype 2273188200 [770,1238,1224,1251] CNCR 1 378 CNCR 35083 30 15 15 paratype 2273188197 2017-04-02 CNCR Laguna El Ojito & L. Garcia-Vazquez & Garcia-Vazquez, J & S. Martinez. Mexico Municipality of Apizaco 19.433332 Laguna El Ojito 21 -98.1 San Luis Apizaquito 1 378 20 10 10 Tlaxcala paratype