Maera umarae, García-Madrigal, María Del Socorro, 2010

García-Madrigal, María Del Socorro, 2010, Littoral Maeridae and Melitidae (Amphipoda: Gammaridea) from the Gulf of Tehuantepec, Mexico, Zootaxa 2623, pp. 1-51 : 34-44

Maera umarae n. sp.

( Figs 17 , 18 )

Type material: 2 specimens: UMAR-PERA-289, holotype male (3.2 mm), paratype female (3.5 mm), specimens mounted (Estacahuite beach, September 10, 2005, intertidal algae, coll. R. Bastida et al.).

Additional material: 18 specimens: UMAR-PERA-290, paratypes 2 females, 2 males, 14 incomplete specimens (La Tijera beach, September 12, 2006, coral rock 4 m, coll. R. Bastida et al.).

Description: based on holotype male, 3.2 mm, UMAR-PERA-289.

Head: medium, similar size as two pereon segments; anterior head lobe ample and rounded, slightly projected, and inferior antennal sinus straight. Eyes subreniform inner line, pigment light brown, length represents approximately 1/4 length of head. Length of antenna 1 is approximately the same as first five segments of pereon, first article of peduncle 1/8 shorter than the second article and considerably thicker, and the length of third article 1/3 the length of second article of peduncle. Accessory flagellum with six articles of the same size with exception of the sixth, which is shorter. Antenna 2 setose, approximately 1/2 the length of antenna 1, length of fifth article 1/3 the length of fourth article; first article of flagellum is 1/3 the length of the fifth article of peduncle.

Pereon: body elongated, length approximately 2.5 times the length of the antenna 1, dorsally smooth; color off-white in alcohol. Coxa 1 subtrapezoid, anterior margin emarginated; coxae 2–4 subquadrangle, coxa 2 with anterior margin rounded and posterior margin emarginated, coxae 3–4 with lateral margins straight and parallel; ventral margin coxae 1, 2 and coxae 4, 5 with one long and some short simple setae on each one; coxae 5–7 with one short robust seta on each one. Gnathopod 1: length of propodus less than 1/2 longer than dactyl, propodus suboval; oblique palm margin, minutely denticulated, with scarce robust setae, two robust setae at inner angle of the palm, one medium and one longer. Gnathopod 2: length of propodus approximately 1/2 longer than dactyl, subrectangle propodus; palm margin slightly oblique, slightly setose, with mediumsized simple setae; palm margin with two teeth, the first near dactylar hinge ample trapezoidal with excavated distal margin, irregular to slightly denticulated. The second ample subquadrate medial tooth, with excavated distal margin, irregular to slightly denticulated; palm defined by a long conical tooth to receive dactyl. Pereopods 1–2 with merus and propodus the same size, basis with short robust setae and short simple setae; pereopods 3–5 with narrow basis, posterior margin slightly straight and propodus 1/4 longer than carpus.

Pleon: epimera medium, outline respective to general line of the body; epimeron 3 with straight posterior edge, posteroventral corner ends in a small spine, and ventral margin bearing short robust setae, formula for epimera is 1:0, 2:1–1–1, 3:1–1–1–1–1. Uropod 3: missing. Telson cleft 2/3 the length of lobes, lobes deeply excavated, inner angle 1/2 shorter than outer angle of each lobe of telson, apices armed with two robust setae, lateral seta 1/3 longer than the medial seta.

Female: based on paratype female, 3.5 mm, UMAR-PERA-289. Palm margin of gnathopod 2 with two dissipated teeth and in the case of the distal margin of the medial tooth continuous subdistally in an irregular margin to slightly denticulated; palm margin of immature female without teeth, with robust setae and medium-sized simple setae. Formula for epimera is 1:0, 2:1–1–1–1, 3:1–1–1–1–1–1. Basis of the pereopods 1–2 with long and short setae. Uropod 3: peduncle 1/3 shorter than the outer ramous, inner ramous slightly shorter to subequal as the outer ramous; external ramous with two segments, inner margin of inner ramous bearing three simple robust setae, external margin of outer ramous with five clusters of robust setae and one robust seta more proximally. Telson cleft, apices armed with two robust setae, lateral seta 1/2 longer than medial seta.

Etymology: the specific name is dedicated to the Universidad del Mar for hosting me and giving me the opportunity to work in this region poorly known, but with high biodiversity, of Mexico.

Taxonomic comments: Maera umarae n. sp. presents characters similar to other species of genus; the most important characters are compared (see Table 5) between the species of Maera from the Tropical Eastern Pacific. The length of article 1 of antenna 1 in Maera similis is 1/5 shorter than the length of article 2, while in Maera umarae n. sp. it is 1/8 shorter than the length of article 2. The ventral margin of article 1 of the antenna 1 in Maera similis has three proximal and one distal short robust seta, while Maera umarae n. sp. has two proximal short robust setae. The accessory flagellum of the antenna 1 in Maera similis has ten articles, while in Maera umarae n. sp. has six articles. The form of the teeth of gnathopod 2 in Maera similis is subquadrate and the distal margin of both teeth is straight, while Maera umarae n. sp. the first tooth near dactylar hinge is subtrapezoid, the medial tooth is subquadrate, and the distal margin of both teeth is concave, irregular to slightly denticulated. The length of the cleft of telson in Maera similis is 3/4 the length of the lobes, while in Maera umarae n. sp. it is 2/3 the length of the lobes. Telson with the inner angle of the lobes in Maera similis is 1/4 larger than the outer angle, while Maera umarae n. sp. is 1/2 shorter than the outer angle. Telson with the length of lateral robust seta in Maera similis is 1/3 shorter than the medial seta, while in Maera umarae n. sp. it is 1/3 to 1/2 larger than the medial seta. The length of the medial robust setae of telson in Maera similis is 2/3 the length of the lobes, while Maera umarae n. sp. is 1/4 the length of the lobes.

TABLE 5. Comparison between males of Maera sensu stricto from the Tropical Eastern Pacific. Maera chinarra Barnard, 1979: 86 , fig. 29 (part).

Quadrimaera chinarra . — Krapp-Schickel & Jarrett 2000: 46.

Type locality: 11 km to south of Cabo San Lucas, Gulf of California.

Distribution: Gulf of California: Espiritu Santo Island, Cabo San Lucas; Central America: Costa Rica (Cocos Islands); Galapagos Islands, Ecuador.

Habitat: intertidal; algal wash, symbiont, Piles of the dock, coral rock, sediments of coral rock, intertidal algae.

Material examined: 347 specimens: UMAR-PERA-291, 8 males, 2 females, 20 juv (Carrizalillo Beach, August 12, 2006 in bivalve, coll. I. Gutiérrez); UMAR-PERA-292, 2 males, 2 females, 1 juv (Puerto Angel, May 20, 2007, algae on piles of the dock 0.5 m, coll. F. Cortés); UMAR-PERA-293, 1 male, 1 female (Estacahuite beach, April 9, 2005, intertidal algae, coll. R. Bastida et al.); UMAR-PERA-294, 8 males, 11 females, 9 juv (Estacahuite beach, May 18, 2005, sediments of coral rock 3–4 m, coll. R. Bastida et al.); UMAR-PERA-295, 1 female (La Tijera beach, April 30, 2005, sediments from coral rock 4 m, coll. R. Bastida et al.); UMAR-PERA-296, 1 male, 3 females, 4 juv (Maguey Bay, July 4, 2007, intertidal algae, coll. B. Martínez et al.); UMAR-PERA-297, 27 males, 43 females, 169 juv (La Entrega Bay, July 4, 2007, intertidal algae, coll. B. Martínez et al.); UMAR-PERA-298, 5 males, 6 females, 23 juv (El Arrocito beach, July 4, 2007, intertidal algae, coll. B. Martínez et al.).

Description: based on male, 4.5 mm, UMAR-PERA-294.

Head: head subrectangle, 1/8 longer than the width; anterior head lobe big, semirounded and projected; inferior antennal sinus slightly excavated to nearly straight, anteroventral margin of this sinus ends in a small spine. Eyes ovate, light brown in alcohol, width of eye is approximately 1/4 length of head. Antenna 1 slightly setose, ventral surface of article 1 of antenna 1 with one proximal short robust setae; length of antenna 1 is more than 1/2 length longer than the body, first article of peduncle 1/5 shorter than the second and both are the same width, the length of third article nearly 2/5 length of second article of peduncle. Accessory flagellum with five articles of the same size, with exception of longer third article. Antenna 2 slightly setose, approximately 1/4 shorter than the antenna 1, fifth article is 1/6 shorter than fourth article; first article of flagellum 1/4 the length of the fifth article of peduncle.

Pereon: body elongate, appears fragile, its length is less than 1/2 longer than the antenna 1, dorsally smooth; color off-white in alcohol. Coxae 1–4 suboval, lateral margins nearly straight; coxa 4 with posterior margin slightly emarginated; coxae 1–4 with medium-sized simple setae, formula for coxae 1–4: 2–1–1–2; coxae 5–7 with one short robust seta on each one. Gnathopod 1: propodus subrectangular, palm oblique and nearly straight, inner surface of propodus with few simple setae, propodus 1/8 shorter than the carpus; distal margin of carpus with serrate setae, carpus 2/3 longer than the ischium. Gnathopod 2: subquadrate propodus, its length 1/5 longer than width; propodus narrows gradually toward distal margin; palm nearly transverse with a medial and wide notch “U” shape, medial tooth follows the general line of palm, angle of palm with a small tooth does not reach the general line of palm. Pereopods strong, basis of pereopods 1–5 subquadrangled; anterior margin of basis of pereopods 1–2 with small simple setae and posterior margin with numerous short robust setae; pereopod 5 stronger and longer, basis 2/5 longer than the merus, merus 1/4 longer than the carpus.

Pleon: posterior margins of the epimera 1–3 convex, posteroventral corner ends in a sharp spine, ventrally setose, formula for epimera 1–3: 1:1, 2:1–1, 3:1–1–1–1–1. Uropod 3: inner ramous 1/3 shorter than the outer ramous; longest apical robust setae of outer ramous 1/5 longer than peduncle; inner margin of inner ramous with one medial robust seta; inner margin of outer ramous with one robust seta; inner margin of peduncle with short simple setae. Telson deeply cleft, with narrow medial gap, inner margin of each lobe convex, distal margin of lobe nearly concave, each lobe with three robust setae and one plumose seta, smallest robust seta less than 1/2 shorter than the longest robust seta, which is 1/4 longer than telson, outer margin each lobe with three plumose setae.

Female: gnathopod 2 of mature female similar to male; occasionally palm margin complete for female juvenile; and both with short robust setae, and medium-sized simple setae. Coxae similar to male but position and number of spines vary in coxae 5–7, formula for coxae 5–7 is 0–1–0. Ventral margin of epimera with short robust setae, formula for epimera is 1–3: 1:0, 2:1–1, 3:1–1–1–1–1.

Taxonomic comments: Quadrimaera chinarra ( Barnard, 1979) is allied with Q. reishi ( Barnard, 1979) the most important characters that separate them are compared (see Table 6). Anteroventral angle of head of Q. chinarra has a small spine, while Q. reishi has a long spine. Ventral surface of article 1 of antenna 1 of Q. chinarra has one proximal short robust seta, while Q. reishi has one distal and two medioproximal short robust setae. Length of article 1 of the antenna 1 of Q. chinarra is 1/5 shorter than article 2, while Q. reishi is the same size as article 2 of antenna 1. Accessory flagellum of antenna 1 of Q. chinarra has five articles, while Q. reishi has seven articles. Length of article 3 of mandibular palp of Q. chinarra is shorter than article 2, while in Q. reishi the length of article 3 and 2 are same. The palm of the gnathopod 2 of Q. chinarra has two teeth and the angle has a small tooth, while Q. reishi has two teeth and the angle has a large tooth. Medial tooth of the palm of the gnathopod 2 of Q. chinarra follows general line of palm, while Q. reishi it does not follow the general line of palm. The inner ramous of the uropod 3 in Q. chinarra is 1/3 shorter than the outer ramous, while the Q. reishi inner ramous is 1/6 shorter than outer ramous. Inner margin of each lobe of telson in Q. chinarra is nearly convex, while in Q. reishi it is nearly straight. The telson of Q. chinarra has three apical robust setae, while Q. reishi has five robust setae. Outer margin of telson of Q. chinarra has three plumose setae, while Q. reishi has two plumose setae and one simple seta.

TABLE 6. Comparison between males of Quadrimaera from the Tropical Eastern Pacific. Maera reishi Barnard, 1979: 83 , figs. 45–47.

Quadrimaera reishi . — Krapp-Schickel & Jarrett 2000: 46.

Type locality: Espiritu Santo Island, Gulf of California.

Distribution: California: from North California to Cayucos; Gulf of California: Bahia de Los Angeles to Espiritu Santo Island; Galapagos Islands, Ecuador.

Habitat: depth 0–6 m; algae, rock wash.

Material examined: 204 specimens UMAR-PERA-299, 10 males, 12 females, 14 juv (Playa del Amor, Zipolite, July 3, 2007, algae from tide pool, coll. J. Jarquín et al.); UMAR-PERA-300, 1 male (Panteon beach, March 23, 2007, coral rock 3 m, coll. V. Mata); UMAR-PERA-301, 11 males, 9 females (Estacahuite beach, April 9, 2005, intertidal algae, coll. R. Bastida et al.); UMAR-PERA-302, 1 male, 1 juv (Estacahuite beach, September 10, 2005, coral rock 2–4 m, coll. R. Bastida et al.); UMAR-PERA-303, 6 males, 6 females, 52 juv (Estacahuite beach, September 10, 2005, intertidal calcareous algae, coll. R. Bastida et al.); UMAR-PERA- 304, 1 male, 2 females, 3 juv (Estacahuite beach, August 25, 2006, coral rock 4 m, coll. R. Bastida et al.); UMAR-PERA-305, 8 males, 5 females, 24 juv (Estacahuite beach, July 3, 2007, intertidad coral rock, coll. J. Jarquín et al.); UMAR-PERA-306, 1 male, 7 females, 21 juv (La Tijera beach, April 30, 2005, sediments from coral rock 4 m, coll. R. Bastida et al.); UMAR-PERA-307, 1 male, 3 females, 4 juv (La Tijera beach, September 12, 2006, coral rock 4 m, coll. R. Bastida et al.); UMAR-PERA-308, 1 juv (El Arrocito beach, May 23, 2000, sediments from coral rock, coll. S. Salazar et al.).

Description: based on male, 6.6 mm, UMAR-PERA-302.

Head: subquadrate, width similar to length; anterior head lobe small and semiround; inferior antennal sinus wide and deeply excavated, anteroventral corner of this sinus ends in a long spine. Eyes ovate, almond pigment; width of eyes approximately 1/6 length of head. Antenna 1 setose, ventral surface of article 1 of the antenna 1 with two medioproximal short robust setae and one distal short robust seta; its length is less than 1/ 2 shorter than the body, first article of peduncle is the same length as the second and slightly thicker, length of third article 1/3 the length of second article of peduncle. Accessory flagellum with seven articles of the same size with exception of the first, which is longer. Antenna 2 setose, approximately 1/4 shorter than antenna 1, the length of fifth article 1/5 the length of fourth article; first article of flagellum 1/5 the length of the fifth article of peduncle.

Pereon: body elongated, appears strong, length more than 1/2 longer than antenna 1, dorsally smooth; color off-white in alcohol. Coxae 1, 3 and 4 subquadrates, lateral margin nearly straight; coxae 2, 4 with posterior margin slightly emarginated; coxae 1–4 with medium and long simple setae, formula for coxae 1–4: 5–1–2–2; coxae 5–7 with short robust setae, formula for coxae 5–7: 1–0–1. Gnathopod 1: propodus suboval, palm oblique and convex, inner surface of propodus with three bundles of setae in a row, propodus 1/10 shorter than the carpus; distal margin of carpus partially covered with serrate setae, carpus approximately 1/2 longer than the ischium. Propodus of gnathopod 2 subrectangular, length 1/3 longer than width; propodus widening toward distal margin, with medial and narrow “U” notch shape, medial tooth does not reach the general line of palm, angle of palm with a long tooth beyond the general line of palm. Pereopods thin, basis of pereopods 1–5 subrectangular, anterior margin of basis of pereopods 1–2 with medium and small simple setae, and posterior margin with some short robust setae; pereopod 5 moderately stronger and longer, basis 1/ 4 longer than merus, merus 1/3 longer than carpus.

Pleon: epimera 1–3 with posterior margins nearly straight to slightly concave, posteroventral corner ends in a small spine, ventrally setose, formula is 1: 1, 2: 1–1–1, 3: 1–1–1–1–1. Uropod 3: inner ramous 1/6 shorter than the outer ramous; longest apical robust seta of the outer ramous same length as peduncle; inner margin of inner ramous with two robust setae, one medial and one subdistal; inner margin of outer ramous with three bundles of robust setae; inner margin of peduncle with simple setae and one short robust seta. Lobes of telson deeply cleft, wide medial gap, inner margin of each lobe nearly straight, distal margin of lobe nearly convex, each lobe with five robust setae and one plumose seta, two robust setae are 1/3 longer than telson, outer margin of each lobe with two plumose setae and one simple seta.

Variation: the palm margin of the gnathopod 2 of mature female is complete, occasionally similar to male. Coxae and epimera in female are similar to male.

Taxonomic comments: see taxonomic comments of Q. chinarra and Table 6.

Figures

FIGURE 17. Maera umarae n. sp., holotype, male, 3.2 mm, UMAR-PERA- 289, Estacahuite beach, Oaxaca: A) habitus; B) coxa 1; C) coxa 2; D) coxa 3; E) coxa 4; F) coxa 5; G) coxa 6; H) coxa 7; I) gnathopod 1, external side; J) gnathopod 1, internal side; K) accessory flagellum; L) antenna 1, left; M) antenna 2, left; N) maxilla 2; O) gnathopod 2, external side; P) gnathopod 2, internal side.

FIGURE 18. Maera umarae n. sp., holotype, male, 3.2 mm, UMAR-PERA- 289, Estacahuite beach, Oaxaca: A) right mandible; B) upper lip; C) lower lip; D) maxilliped; E) pereopod 1; F) pereopod 2; G) pereopod 3; H) left pereopod 5; I) telson; J) uropod 1; K) uropod 2. Paratype, female, 3.5 mm, UMAR-PERA- 289, Estacahuite beach, Oaxaca: L) maxilla 1; M) pereopod 4; N) gnathopod 2; O) uropod 3; P) telson; Q) epimera.