Nannastacus corallinus, Jarquín-González, Jani & García-Madrigal, María Del Socorro, 2013

Jarquín-González, Jani & García-Madrigal, María Del Socorro, 2013, Annotated checklist and keys for cumaceans (Crustacea: Peracarida) from the Tropical Eastern Pacific, with six new species from the Southern Mexican Pacific, Zootaxa 3721 (3), pp. 201-257 : 241-247

Nannastacus corallinus sp. nov.

Figs 22–25

Type material. Holotype male, UMAR-Pera 519, San Agustin Bay, Huatulco, Oaxaca, in coral, littoral, 23 February 2010. Paratypes, 1 ovigerous female, UMAR-Pera 520, Coral Beach, Ixtapa Island, Guerrero, coral, 1.5 m, 19 September 2007; 1 male (dissected), 4 ovigerous females (one dissected), 6 females, 26 juveniles, UMAR- Pera 521, San Agustin Bay, Huatulco, Oaxaca, in coral, littoral, 23 February 2010.

Diagnosis. In both sexes: Carapace with three cuspidate setae on each lateral margin of the fifth pleonite. Male. Carapace with seven teeth on each lateral margin. Female. Carapace with six teeth on each lateral margin.

Description. Adult male, 2.3 mm ( Figs 22 A–B). Body flattened. Carapace with seven teeth on each lateral margin and five pairs of fine hairlike setae on dorsal surface; ocular lobe united medially, with a medial constriction, with lenses, and about half the length of carapace; pseudorostrum broad at base and with teeth on distal margin; siphon united medially. All pereonites and first three pleonites with teeth and tubercles on dorsal surface; second and third pleonites with two cuspidate setae on each lateral margin; fifth pleonite with three pairs of cuspidate setae; sixth pleonite shorter than uropod. Exopods on maxilliped 3 and pereopods 1–4.

Antenna 1 ( Fig. 22 C) with first basal article longer than the next two articles together; second article broader and shorter than third article, with a lateral tubercle; main flagellum three-articulated; accessory flagellum uniarticulate. Mandible ( Fig. 22 D) incisor process with three cusps, lacina mobilis absent. Maxilliped 1 similar to the female, with dactylus ( Fig. 22 E) modified as a globular structure. Maxilliped 2 ( Fig. 22 F) with basis shorter than the rest of the articles together; ischium short and bare; merus narrow at base, with fine hairlike setae on dorsal surface and outer margin; carpus and propodus of the same length; dactylus shorter than propodus, with a strong serrate seta. Maxilliped 3 ( Fig. 23 A) with basis broad; ischium short and bare; merus shorter than carpus; carpus and propodus of the same length; propodus longer than dactylus; dactylus with two terminal serrate setae.

Pereopod 1 ( Fig. 23 B) with basis shorter than the rest of the articles together; merus approximately half the length of the carpus; carpus and propodus of similar length; propodus longer than dactylus; dactylus with terminal serrate seta. Pereopod 3 ( Fig. 23 C) with broad basis, shorter than the rest of the articles together; ischium about a half the length of the merus; merus broader than carpus; carpus shorter than propodus; propodus longer than dactylus; dactylus curved. Pereopod 4 ( Fig. 23 D) with broad basis; ischium reduced; merus longer than carpus; carpus longer than propodus; propodus shorter than dactylus; dactylus curved. Pereopod 5 ( Fig. 23 E) with basis shorter than the rest of the articles together; merus shorter than carpus; carpus and propodus of the same length; dactylus pointed and curved.

Uropod ( Fig. 23 F) with peduncle shorter than rami; exopod shorter than endopod and biarticulate, basal article about a third of the length of the distal article, distal article with an apical long seta; endopod uniarticulate.

Ovigerous female, 2.0 mm (Fig. 24A). The overall appearance resembles the male. Carapace with six teeth on each lateral margin; second and third pleonite with a cuspidate seta on each lateral margin.

Antenna 1 (Fig. 24B) similar to the male but with main flagellum biarticulate. Labium (Fig. 24C) with some fine hairlike setae and a cusp on endite. Mandible (Fig. 24D) with a tooth on molar. Maxillule (Fig. 24E) with two endites, outer endite with nine cuspidate setae and inner endite with three setae; palp with two setae. Maxilla (Fig. 24F) with three endites, broad endite with 15 setae and three pappose setae, medial narrow endite with four setae and distal narrow endite with three setae. Maxilliped 1 (Fig. 24G) with ischium fused to the basis; merus broader than long; carpus broader than propodus, with six tridentate flattened setae on the inner margin; propodus longer than dactylus; endite with two hooks on the inner margin, two flattened setae and three apical setae. Maxilliped 2 (Figs 24H) similar to the male, with ischium fused to the basis. Maxilliped 3 ( Fig. 25 A) with basis narrow; ischium fused to the basis; carpus longer than propodus.

Pereopod 1 similar to the male. Pereopod 2 ( Fig. 25 B) basis partially lost; ischium reduced; merus shorter than carpus; carpus narrow at base; propodus shorter than dactylus; dactylus with five cuspidate setae. Pereopod 3 ( Fig. 25 C) with narrow basis, longer than wide; merus narrower than carpus. Pereopod 4 ( Fig. 25 D) with narrow basis; ischium and merus of the same length; carpus shorter than propodus. Pereopod 5 ( Fig. 25 E) carpus shorter than propodus; propodus longer than dactylus.

Uropod ( Fig. 25 F) similar to the male, but the basal article of the exopod approximately a fifth the length of the distal article.

Etymology. The species name refers to the substrate where the specimens were collected, coral.

Remarks. At the present time, about 45 species of Nannastacus have been described, but there are not any described from the eastern Pacific. Although N. corallinus is clearly distinguished from all the other species of Nannastacus by the number of teeth on the lateral margin of the carapace, the most similar species is Nannastacus gamoi occidentalis Petrescu, 2001 from Tanzania because of the presence of strong cuspidate setae on the lateral margins of the body.

The differences between females of Nannastacus corallinus and N. gamoi occidentalis are: N. corallinus has the carapace sub-quadrangular, while in N. gamoi occidentalis it is sub-oval; N. corallinus has the ocular lobe about half the length of the carapace, whereas in N. gamoi occidentalis the ocular lobe is as long as the carapace; N. corallinus has only four pairs of setae on the dorsal surface of the carapace, while N. gamoi occidentalis has 18 setae and teeth; N. corallinus has six teeth on each lateral margin of the carapace, while N. gamoi occidentalis has four teeth on each side; N. corallinus only has a pair of teeth on the dorsal surface of the first two pleonites, while N. gamoi occidentalis has a pair of teeth in all pleonites; N. corallinus has three cuspidate setae on each lateral margin of the fifth pleonite, whereas N. gamoi occidentalis has only a cuspidate seta on each side; N. corallinus has the last pleonite with bare lateral margins, while N. gamoi occidentalis has a cuspidate seta on each side; N. corallinus has the uropod with the exopod more than half the endopod length, whereas in N. gamoi occidentalis the exopod is half the length of the endopod. We only compare females because the male of N. gamoi occidentalis is unknown.

According to the diagnosis of Watling (1991b) Nannastacus corallinus is similar to the genus Scherocumella because it has the branchial siphons separate and united medially and the uropod exopod basal article normal, not submerged in the peduncle. However, this species is included in Nannastacus because it has short pseudorostral lobes directed slightly upward, the uropod peduncle slightly longer or equal to the length of the pleonite six, and the exopod shorter than the terminal seta.

Figures

FIGURE 22. Nannastacus corallinus, Paratype male, 2.3 mm, UMAR-Pera 521, San Agustín Bay, Huatulco, Oaxaca: A) habitus dorsal view; B) habitus lateral view; C) antenna 1; D) mandible; E) distal article of the maxilliped 1; F) maxilliped 2.

FIGURE 23. Nannastacus corallinus, Paratype male, 2.3 mm, UMAR-Pera 521, San Agustín Bay, Huatulco, Oaxaca: A) maxilliped 3; B) pereopod 1; C) pereopod 3; D) pereopod 4; E) pereopod 5; F) uropod.

FIGURE 25. Nannastacus corallinus, Paratype ovigerous female, 2.0 mm, UMAR-Pera 521, San Agustín Bay, Huatulco, Oaxaca: A) maxilliped 3; B) pereopod 2; C) pereopod 3; D) pereopod 4; E) pereopod 5; F) uropod.