New genus and four new species of anthuroid isopods (Crustacea: Peracarida) from southern Mexican Pacific Author Jarquín-Martínez, Ubaldo Laboratorio de Sistemática de Invertebrados Marinos (LABSIM), Universidad del Mar, campus Puerto Ángel, Ciudad Universitaria, Puerto Ángel, Oaxaca, México, 70902 Author García-Madrigal, María Del Socorro 0000-0003-4279-9116 Laboratorio de Sistemática de Invertebrados Marinos (LABSIM), Universidad del Mar, campus Puerto Ángel, Ciudad Universitaria, Puerto Ángel, Oaxaca, México, 70902 & ms _ garcia _ m @ hotmail. com; https: // orcid. org / 0000 - 0003 - 4279 - 9116 ms_garcia_m@hotmail.com text Zootaxa 2021 2021-10-05 5048 1 31 57 journal article 10.11646/zootaxa.5048.1.2 1175-5326 5549145 CD0AF5A5-B9A4-41F5-8F02-6E443CDE05A6 Key to species of Anthuroidea from the Mexican Pacific 1 Articles 3–5 of antenna peduncle with sucker-like cuticular structure, antennal flagellum with more than 30 articles ( Fig. 2D )........................................................... Negoescuanthura bastidai n. gen., n. sp. ( Fig. 2A ) - Antenna peduncle articles 3–5 without suck-like cuticular structure, antennal flagellum less than 30 articles............. 2 2(1) Telson with one pair of statocysts......................................................................... 3 - Telson without statocysts.............................................................................. 13 3(2) Pleonites 1–5 fused.................................................................................... 4 - Pleonites 1–3 free, pleonite 4–5 fused............ Amakusanthura guerrerensis Jarquín-Martínez & García-Madrigal, 2021 4(3) Eyes absent; mandibular palp of two articles................................................................ 5 - Eyes present; mandibular palp of three articles.............................................................. 6 5(4) Distal article of mandibular palp with six medial setae and one apical, lacinia with approximately eight denticles…............................................................................. Cortezura penascoensis Schultz, 1977 - Distal article of mandibular palp with three medial setae and one apical, lacinia with approximately 13 denticles............................................................... Cortezura caeca Jarquín-Martínez & García-Madrigal, 2021 6(4) Pereopods 4–7 with carpus more or less triangular, upper margin much shorter than posterior margin................... 7 - Pereopods 4–7 with carpus more or less rectangular, upper margin nearly as long as posterior margin................................................................................ Haliophasma geminata Menzies & Barnard, 1959 7(6) Maxillipedal palp with two free articles.................................................................... 8 - Maxillipedal palp with more than two free articles........................................................... 9 8(7) Distal article of mandibular palp with one apical seta; palm of pereopod 1 without projection....................................................................... Tinggianthura mexicana Jarquín-Martínez & García-Madrigal, 2021 - Distal article of mandibular palp with two apical setae; palm of pereopod 1 projected...... Cyathura munda Menzies, 1951 9(8) Base of mouthparts with medioventral toothlike process. Skuphonura oaxaquensis Jarquín-Martínez & García-Madrigal, 2021 - Base of mouthparts without medioventral toothlike process................................................... 10 10(9) Body densely pigmented.............................................................................. 11 - Body with little pigment............................................................................... 12 11(10) Inner angle of second antennal article strongly projected; palm of pereopod 1 without projection................................................................... Mesanthura antenniformis Jarquín-Martínez & García-Madrigal, 2021 - Inner angle of second antennal article not projected; palm of pereopod 1 staggered............................................................................. Mesanthura estacahuitensis Jarquín-Martínez & García-Madrigal, 2021 12(10) Body with disordered pigment; last article of mandibular palp with row of 10 setae.......................................................................................................... Mesanthura nubifera Wägele, 1984 - Body with circular pigment; last article of mandibular palp with row of five setae.............................................................................................. Mesanthura occidentalis Menzies & Barnard, 1959 13(2) Body with seven large pereonal segments; mandible with palp of 3 articles....................................... 16 - Body with six large pereonal segments; mandible without palp................................................ 14 14(13) Pleonites 1–5 fused with suture lines; pleonite 1 twice as long as pleonite 2...................................... 15 - Pleonites 1–5 fused without suture lines; pleonites of similar lengths.......... Califanthura squamosissima ( Menzies, 1951 ) 15(14) Pleon longer than pereonites 6+7 and as wide as long; telson 1.3 times as long as pleon and twice as long as wide.................................................................................... Colanthura bruscai Poore, 1984 - Pleon shorter than pereonites 6+7 and 1.2 times width than long ( Fig. 5A, B ); telson 0.9 times as long as pleon and 2.2 times longer than wide ( Fig. 5C ).......................................................... Colanthura gabinae n. sp. 16(13) Pleonites fused; antennule flagellum of three articles; mandibular palp distal article with row of 6–7 robust setae............................................................................. Paranthura californiae Nunomura, 1978 - Pleonites free; antennule flagellum more than three articles; mandibular palp distal article with row more than seven robust setae.............................................................................................. 17 17(16) Pleonites free and articulated........................................................................... 18 - Pleonite 1 free, pleonites 2–5 fused...................................................................... 19 18(17) Distal article of mandibular palp with 14 robust setae; telson ovate................... Paranthura elegans Menzies, 1951 - Distal article of mandibular palp with 16 robust setae; telson rectangular with distolateral margins folder over dorsum….......................................................................... Paranthura longitelson Wägele, 1984 19(17) Body with pigment spots in all somites and telson, pereonites 2–5 of body with central pigment spot ( Fig. 8A ); antennule flagellum of seven articles ( Fig. 8B )..................................................... Paranthura amorensis n. sp. - Pereonite 4 and 5 with pigment line ( Fig. 11A ); antennule flagellum of five articles ( Fig. 11B )..... Paranthura tientai n. sp.