Mesanthura estacahuitensis Jarquín-Martínez & García-Madrigal 2021, sp. nov.

Mesanthura estacahuitensis sp. nov.

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Figs 11–13, 20D, Table 1

Etymology

This species is named after its type locality, Estacahuite Beach, Oaxaca.

Material examined

Holotype MEXICO • ♀ (body length 6.8 mm); Oaxaca, 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 547.

Description

Holotype (♀, UMAR-PERA 547)

BODY (Figs 11A, 20D). Length 6.8 mm, 11.1 times as long as wide, strongly pigmented; cephalon almost as wide as long, circular eyes, in lateral position, rostrum slightly shorter than lateral angles; body proportion: C<1=2>3<4=5>6>7. Pereonites 2–3 cylindrical, 4–6 rectangular, pereonite 7 square; pleonites 1–5 fused, slightly wider than long, 0.9 times as long as pereonite 7, pleonite 6 free with a medial incision on the distal margin; telson linguiform, medially wider, 1.8 times as long as wide, apex broadly rounded with three pairs of long smooth setae and one pair of short plumose setae; one pair of proximal statocysts.

ANTENNULE (Fig. 11B). Peduncle with three articles; article 1 sub-equal in length to articles 2 and 3 together with plumose sensory setae; article 2 sub-square with distal plumose sensory setae; article 3 rectangular, 2.1 times as long as wide; flagellum with three articles, article 1 tiny with one plumose sensory seta; article 2 longest, 0.6 times as long as last peduncle article; article 3 with four aesthetascs and three long simple setae.

ANTENNA (Fig. 11C). Peduncle with five articles; articles 2–5 with grooved external margin, article 2 sub-square; article 3 shorter than the others; article 4 square; last article 1.3 times as long as article 4 with a group of apical setae; flagellum 0.6 times as long as last peduncle article with four articles decreasing distally and with numerous fine setae.

MAXILLIPED (Fig. 11D). Palp with three articles. Article 1 rectangular, 1.3 times as wide as long with a long seta in the internal distal angle; article 2 with two setae in the inner angle; article 3 oblique, with five setae, one proximal and two distal plumose.

MAXILLA (Fig. 11E). Slender, bent distally with five teeth.

MANDIBLE (Fig. 11F). Symmetrical; palp with three articles, article 1 rectangular, almost half the length of second; article 2 with an apical seta; article 3 with eight serrated robust setae. Incisor with three teeth; lacinia mobilis with four denticles and molars rounded.

PEREOPOD 1 (Fig. 12A). Subchelate; carpus triangular, rounded distally, with three long setae; propodus oval, 2 times as long as wide, palm projected medially with crenulated margin, proximal region with a row of four setae, distal region with a group of smooth setae; dactylus reaching the projection of the palm with two long setae in internal distal angle.

PEREOPODS 2–3 (Fig. 12B–C). Similar in shape and size. Carpus triangular, with three apical setae; propodus sub-cylindrical, 2.2 times as long as wide in P2 and 2.7 times as long as wide in P3, internal margin with scales, ventrodistal angle with a denticulate sensory spine; distal margin of dactylus with a spine and a group of smooth and plumose setae.

PEREOPODS 4–7 (Fig. 12D–G). Similar in shape and size. Carpus sub-pentagonal with a sensory spine on the ventrodistal margin, external margin with a plumose sensory seta; propodus cylindrical, slightly curved, internal margin with setulated scales; ventrodistal angle with a denticulate sensory spine and two pectinate spines in P7; dactylus with a denticle in the internal proximal margin.

PLEOPOD 1 (Fig. 13A). Protopod with five retinaculae; exopod operculiform, 3.3 times as wide as the endopod, surrounded distally by 26 plumose setae; endopod slightly shorter than exopod, apically rounded with seven plumose setae.

PLEOPOD 2 (Fig. 13B). Exopod cylindrical, longer than endopod, surrounded distally by eight plumose setae; endopod with five plumose setae.

UROPODAL PROTOPOD (Fig. 13F). Rectangular, 1.6 times as long as wide with a row of plumose setae on the inner margin.

UROPODAL ENDOPOD (Fig. 13F). Oval, 1.3 times as long as wide, distal region with smooth and plumose sensory setae.

UROPODAL EXOPOD (Fig. 13G). Oval with a strong emargination on the distal region; margin with approximately 20 smooth setae and 30 plumose setae.

Distribution and habitat

Known only in the type locality, Estacahuite Beach, Oaxaca. In coral rock; subtidal (4 m).

Remarks

Mesanthura estacahuitensis sp. nov. differs from previously recorded species of Mesanthura by the following unique characteristics: pigmentation pattern, last article of mandibular palp with eight setae, palm of pereopod 1 crenulated and projected medially. Mesanthura estacahuitensis sp. nov. is more similar to M. nubifera, described from Turner Island, Sonora than to the other species (Table 1) as follows: (1) projection to palm of pereopod 1, (2) mandible, (3) shape and dorsal ornamentation of the telson. However, in M. estacahuitensis sp. nov. the distal article of the antennular flagellum has four aesthetascs, flagellum of antenna with four articles, last article of maxillipedal palp with three plumose setae, internal margin of the carpus and propodus of the pereopods 2–7 with setulated scales and 1–2 simple setae, apical region of the telson with three pairs of simple setae and one pair of plumose setae, while M. nubifera has antennule with five aesthetascs, antennal flagellum with one article, last article of maxillipedal palp with one plumose seta and two pectinate setae, carpus and propodus of the pereopods 2–7 with cuticular scales and up to seven simple setae, and telson with nine pairs of apical setae.