Mesanthura antenniformis, Jarquín-Martínez & García-Madrigal, 2021

Jarquín-Martínez, Ubaldo & García-Madrigal, María del Socorro, 2021, Six new species of Anthuridae (Peracarida: Isopoda) from the southern Mexican Pacific, European Journal of Taxonomy 760 (1), pp. 61-100 : 74-79

publication ID	https://doi.org/ 10.5852/ejt.2021.760.1441
publication LSID	lsid:zoobank.org:pub:666AD5F1-6AC4-4940-B05C-4B57C3063593
DOI	https://doi.org/10.5281/zenodo.5123268
persistent identifier	https://treatment.plazi.org/id/8C5D87D5-BA42-FFBB-FD9D-9724FC714A64
treatment provided by	Felipe
scientific name	Mesanthura antenniformis
status	sp. nov.

Treatment

Mesanthura antenniformis View in CoL sp. nov.

urn:lsid:zoobank.org:act:CD29F376-B134-4D1B-9CAD-F163AB552D11

Figs 8–10 View Fig View Fig View Fig , 20C View Fig , Table 1 View 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 . GoogleMaps

Paratypes MEXICO • 1 ♂ (body length 4.1 mm); same collection data as for holotype; UMAR-PERA 543 GoogleMaps • 6 ♀♀ (ovigerous), 1 ♀, 1 ♂; same collection data as for holotype; UMAR-PERA 544 GoogleMaps .

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 GoogleMaps • 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 GoogleMaps • 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 GoogleMaps • 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 GoogleMaps • 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 GoogleMaps .

Description

Holotype (♀ (ovigerous), UMAR-PERA 542)

BODY ( Figs 8A View Fig , 20C View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ). Slender, bent apically with seven teeth.

MANDIBLE ( Fig. 8E View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ). Oval and elongated; exopod shorter than endopod, surrounded apically by 10 plumose setae; endopod with seven plumose setae.

UROPODAL PROTOPOD ( Fig. 10C View Fig ). Uropodal protopod 2.3 times as long as endopod with plumose setae on the external margin.

UROPODAL ENDOPOD ( Fig. 10C View Fig ). Oval, distally narrower, 1.6 times as long as wide, margin with simple and plumose setae.

UROPODAL EXOPOD ( Fig. 10C View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ). 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 View 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.