Mesanthura antenniformis Jarquín-Martínez & García-Madrigal 2021, sp. nov.
Creators: name: Jarquín-Martínez, Ubaldo
name: García-Madrigal, María del Socorro
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Anthuridae
Mesanthura
Mesanthura antenniformis

description: Mesanthura antenniformis sp. nov.
urn:lsid:zoobank.org:act: CD29F376-B134-4D1B-9CAD-F163AB552D11
Figs 8–10, 20C, Table 1
Etymology
The name ‘ antenniformis ’ refers to the peculiar shape of the second antenna article of this species.
Material examined
Holotype MEXICO • ♀ (ovigerous, body length 8 mm); Oaxaca, Puerto Ángel, Estacahuite Beach; 15°40′ N, 96°29′ W; depth 7 m; 17 Apr. 2008; S. Salazar-Vallejo et al. leg.; dead coral; UMAR-PERA 542.
Paratypes MEXICO • 1 ♂ (body length 4.1 mm); same collection data as for holotype; UMAR-PERA 543 • 6 ♀♀ (ovigerous), 1 ♀, 1 ♂; same collection data as for holotype; UMAR-PERA 544.
Additional material
MEXICO – Oaxaca • 1 ♀ (ovigerous); Cozoaltepec, Agua Blanca Beach; 15°44′2″ N, 96°48′32″ W; depth shallow water; 2 Apr. 2009; J. León-Robles leg.; fouling algae; UMAR-PERA 539 • 1 ♀ (ovigerous), 1 ♀; Puerto Ángel Dock; 15°39′56″ N, 96°29′27″ W; depth 3 m; 12 Jul. 2019; Y. Chávez- López and A. Pérez-Chávez leg.; tubes of sabellariids; UMAR-PERA 540 • 1 ♀ (ovigerous); Puerto Ángel, Estacahuite Beach; 15°40′ N, 96°29′ W; depth 2–4 m; 10 Sep. 2005; J.R. Bastida-Zavala et al. leg.; tubes of sabellariids; UMAR-PERA 541 • 1 ♀, 2 ♂♂, 5 mancae; Puerto Ángel, Estacahuite Beach; 15°40′ N, 96°29′ W; depth 7 m; 17 Apr. 2008; S. Salazar-Vallejo et al. leg.; rock; UMAR-PERA 545 • 3 ♀♀, 3 ♂♂, 5 mancae; Puerto Ángel, Estacahuite Beach; 15°40′ N, 96°29′ W; depth 2–4 m; 10 Sep. 2005; J.R. Bastida-Zavala et al. leg.; coral rock; UMAR-PERA 546.
Description
Holotype (♀ (ovigerous), UMAR-PERA 542)
BODY (Figs 8A, 20C). Length 8 mm, 7.7 times as long as wide, pigmented; cephalon almost half the length of the first pereonite; rostrum prominent and acute, sub-equal to the distal angles of the cephalon; small eyes located on the anterolateral edges of the head, not distinguishable ommatidia; body proportion: C<1>2<3<4=5>6>7. Pereonite 7 slightly wider than length; pleonites 1–5 fused, sub-equal to pereonite 7; telson linguiform, slightly shorter than uropodal endopod, rounded distal region, apex slightly emarginated with six pairs of setae; proximal part with one pair of statocysts.
ANTENNULE (Fig. 8B). Peduncle with three articles. Article 1 rectangular, 1.3 times as long as the second and third together with plumose sensory setae; article 2 half of the 3; flagellum with three articles, sub equal to the last peduncular article, distal article with 5–6 aesthetascs and simple setae.
ANTENNA (Fig. 8C). Peduncle with five articles. Second article 1.4 times as long as the subsequent peduncular articles; internal angle projected with two simple setae, distal margin with small sinuosities; article 3 partially covered by second article; last article 1.1 times as long as article 4 with simple and sensory plumose setae in the distal region; flagellum with five articles, sub-equal to the length of the last peduncle article, square article with numerous thin setae.
MAXILLIPED (Fig. 8D). Palp with three articles. Article 1 rectangular, half the length of the second with a single ventrodistal seta; distal article small, oblique with six setae, proximal and distal plumose setae, a medial pectinate seta and a simple one.
MAXILLA (Fig. 8F). Slender, bent apically with seven teeth.
MANDIBLE (Fig. 8E). Symmetrical; palp with three articles, article 2 cylindrical, 2.2 times as long as the first with a subdistal seta; distal article with 5–6 robust marginal setae; incisor with three teeth; lacinia mobilis with five denticles and small molars.
PEREOPOD 1 (Fig. 8G). Subchelate; carpus triangular, apical margin rounded with four simple setae; palm slightly convex with four marginal setae, distal margin crenulated; dactylus with a spine in the distoventral angle and a group of setae.
PEREOPODS 2–3 (Fig. 9A–B). Similar in shape and size. Carpus triangular with three apical setae; propodus elongated, cylindrical, 2.1–2.2 times longer than wide, ventral margin slightly curved with two long setae, distoventral angle with a denticulate sensory spine; dactylus curved with one spine and a group of distal setae.
PEREOPODS 4–7 (Fig. 9C–F). Similar in shape and size. Carpus trapezoidal with a sensory spine at the ventrodistal margin and three simple setae, external margin with a plumose sensory seta; propodus cylindrical with a denticulate sensory spine at the distal inner angle; dactylus curved. Pereopod 7 propodus with setulated scales and two robust pectinate spines on internal angle. Propodus of all pereopods with plumose sensory setae.
PLEOPOD 1 (Fig. 10A). Protopod with five retinaculae; exopod operculiform, almost two times as long as wide, sinuous distal margin, surrounded by 31 plumose setae; endopod sub-equal to the length of the exopod and 0.3 times its width, surrounded apically by 10 plumose setae.
PLEOPOD 2 (Fig. 10B). Oval and elongated; exopod shorter than endopod, surrounded apically by 10 plumose setae; endopod with seven plumose setae.
UROPODAL PROTOPOD (Fig. 10C). Uropodal protopod 2.3 times as long as endopod with plumose setae on the external margin.
UROPODAL ENDOPOD (Fig. 10C). Oval, distally narrower, 1.6 times as long as wide, margin with simple and plumose setae.
UROPODAL EXOPOD (Fig. 10C). Sub-equal in length to the protopod, oval, distally emarginated, external margin strongly crenulated with plumose and simple setae.
Male (dimorphic characters; based on the paratype ♂, UMAR-PERA 543)
ANTENNULE (Fig. 10D). Robust; articles 1 and 2 with plumose sensory setae, article 1 rectangular, 2.4 times as long as second; article 2 and 3 sub-equal in length; flagellum with six articles, articles 2–5 with numerous aesthetascs; distal article with a group of long setae.
PEREOPOD 1 (Fig. 10E). Subchelate; carpus distal part truncated with crenulated margin; palm with a step-like proximal process with robust setae, distal margin crenulated, mesial region with numerous setae.
PLEOPOD 2 (Fig. 10F). Exopod shorter than endopod, surrounded apically by seven plumose setae; endopod surrounded apically by four plumose setae; male appendix cylindrical with scales in distal region.
Distribution and habitat
Central coast of Oaxaca, from Agua Blanca to Estacahuite Beach. In coral, tubes of sabellariids, rocks and algae; intertidal to subtidal (7 m).
Remarks
Mesanthura antenniformis sp. nov. differs from previously recorded species of Mesanthura in the following unique characteristics: second article of antenna strongly projected and winding on the distal margin; palm of pereopod 1 straight. Between the three eastern Pacific species (Table 1), M. antenniformis sp. nov. is more similar to M. occidentalis, described from Point Conception, California, by the following characteristics: (1) last article of mandibular palp with five setae, (2) dorsal surface of the telson with some setae; however, differs because in that M. antenniformis sp. nov. has a dense pigmentation pattern, the palm of pereopod 1 is straight with the distal margin crenulate, propodus of pereopod 2 with setulated scales, apical part of the telson slightly emarginated and with six pair of setae, while, M. occidentalis has a slightly pigmented body in a circular pattern, palm of pereopod 1 medially projected, propodus of pereopod 2 with cuticular scales and the telson has eight pairs of setae.
description: Published as part of Jarquín-Martínez, Ubaldo & García-Madrigal, María del Socorro, 2021, Six new species of Anthuridae (Peracarida: Isopoda) from the southern Mexican Pacific, pp. 61-100 in European Journal of Taxonomy 760 (1) on pages 74-79, DOI: 10.5852/ejt.2021.760.1441, http://zenodo.org/record/5121764