Nematocarcinus gralicipes Filhol, 1884

Souza-Filho, Jesser Fidelis De, 2017, Deep sea decapod crustaceans of São Pedro and São Paulo Archipelago, Equatorial Atlantic, Brazil, Zootaxa 4324 (2), pp. 331-347 : 340

Nematocarcinus gralicipes Filhol, 1884

( Figure 7 )

Nematocarcinus gralicipes — Filhol, 1884: 232, fig. 1.— Crosnier & Forest, 1973:123, fig. 34-35.— Neves, 1982: 1, fig. 1-2.— Burukovsky, 2009: 83, fig. 1.— Cardoso & Burukovsky, 2014: 440, fig. 2-4.

Nematocarcinus agassizii Faxon, 1893: 204 .— Cardoso & Burukovsky, 2014: 441.

Material examined. 14 specimens, MOUFPE 15260 , São Pedro e São Paulo Archipelago (0°55'681''N e 29°19' 804''W), 700 m, 12/29/2013.

Diagnosis. Body moderately slender; integument moderately hard, not membranous, surface smooth, shiny. Rostrum proximally horizontal, distally it slightly rises up; rostrum length 70–96%, in the extreme case up to 120%, of carapace length; rostrum dorsal margin (including postrostral crest) with 19–36 (usually 23–32) tightly fitting teeth; rostrum ventral margin with 1–5, usually 3–4 teeth, lying in the region of the rostrum free of dorsal teeth. Eyes normally developed, its width noticeably larger than the diameter of the eye stalk. Posterodorsal margin of third abdominal somite poorly developed. Continuation of its sides when crossing forms an obtuse angle close to 90°. Fifth abdominal somite pleura with its sides intersecting at an angle with less than 90°; armed with a little spine, which axis coincides or nearly coincides with the bisector of the angle in adult specimens (carapace length of 15mm or more), in small shrimps the lower margin of the pleura is rounded and the spine is absent. Tubercles, rollers and other elevation on the inner surface of the anterior margin of the pleura of the fifth abdominal somite are absent. Distoventral organ at sixth abdominal somite formed by two single parallel rows of setae that begins with long plumose setae and at the proximal third of sixth abdominal somite length turns to short spindle shaped setae (not plumose) that extends to more than a half of the length of spots; spots located at the sideways surface of sixth abdominal somite; spots more or less oval or teardrop shaped; spots length not more than 1.5 times its width, distance between them 2–2.5 times its width. Telson with 6–9 (usually 7–8) pairs of dorsolateral spines; usually with one accessory spine, occasionally specimens with two or without accessory spines can be found (modified from Cardoso & Burukovsky, 2014).

Distribution. According to Burukovsky (2009), N. gracilipes has a distribution similar to many species that occur in the Portuguese coast and the Mediterranean Sea. It is common in the slope of the Moroccan coast ( Burukovsky, 2012) and the Azores Archipelago, Cape Verde Archipelago and around Ascension ( Crosnier & Forest, 1973). The occurrence in the Mid-Atlantic Ridge north of the Azores ( Burukovsky, 2009) and South of the Equator, including the Brazilian coast ( Cardoso & Burukovsky, 2014), confirms that the species prefers areas of seamounts. This is the first record of this species for the SPSPA, expanding its range of occurrence to the equatorial region of the Atlantic.

Remarks. The Nematocarnidae family has five genera ( Lenzicarcinus , Lipkius , Nematocarcinus , Nigmatullinus , Segonzackomaius ), with Nematocarcinus being the most numerous, with 48 species, among which stands out N. gracilipes (De Grave & Fransen, 2011) . Nematocarcinus gracilipes differs from other species of the genus mainly by having: the rostrum in mature specimens overreaching antennular peduncle with more than one third of its length and reaching scaphocerite distal margin or slightly overreaching it; distoventral organ at sixth abdominal somite formed by spots 1.5–2 times longer than wide; and by single parallel rows of long plumose setae that are replaced by short spindle shaped setae (not plumose) at the proximal third and sixth abdominal somite, extending to more than a half of spots length ( Cardoso & Burukovsky, 2014).

Figures

FIGURE 7. Nematocarcinus gracilipes, female (14.89 mm CC) collected off São Pedro e São Paulo Archipelago, Brazil, MOUFPE 15260. a) Lateral view of carapace; b) lateral view of abdominal somites 1 – 6. Scale bars 5 mm.