Tuesday, February 25, 2020

[Crustacea • 2020] Pugnatrypaea emanata • A New Mud Shrimp of the Genus Pugnatrypaea (Decapoda: Callianassidae) from Outer Continental Shelf Waters of the northern Gulf of Mexico, commonly associated with Hydrocarbon Seeps

Pugnatrypaea emanata  
Felder & Robles, 2020

A new species of callianassid mud shrimp is described from outer continental shelf waters of the northwestern Gulf of Mexico, where it appears to commonly live in close association with sediments on or near natural hydrocarbon seeps. Recent genus-level taxonomic revisions of the Callianassidae, based on gene sequence analyses and comparative morphological studies, included specimens representing this new species, assigning it with strong support to the genus Pugnatrypaea Poore et al., 2019. The other known species of this genus are also typically found in offshore waters of continental shelves, but are all restricted in distribution to the Indo-West Pacific and are known from relatively few specimens. Collections of this new Gulf of Mexico representative of the genus are all from slightly deeper waters than for other known congeners, and commonly occur near hydrocarbon seeps, on some occasions being directly associated with sulfidic substrates that include waxy crude oil globules.

Keywords: Crustacea, Decapoda, Callianassidae

Infraorder Axiidea de Saint Laurent, 1979
Superfamily Callianassoidea Dana, 1852
Family Callianassidae Dana, 1852

Pugnatrypaea Poore, Dworschak, Robles, Manetlatto & Felder, 2019

Figure 3. Pugnatrypaea emanata n. sp.
male holotype, pocl 8.6 mm, northwestern Gulf of Mexico, near Bush Hill hydrocarbon seep, 560 m depth (USNM 1559553 = ULLZ 17962);
ovigerous female paratype, pocl 7.8 mm, northwestern Gulf of Mexico, 610–850 m depth (USNM 1543633 = ULLZ 8280).

Pugnatrypaea emanata n. sp.

Callianassidae (an undescribed genus).–Martin & Haney 2005:500.
Callianassa ? sp. GMX-1, GMX-2.–Felder & Robles 2009: 336, 339, fig. 1 (part), table 1 (part).
Pugnatrypaea GMX.–Robles et al. 2020 (in press: proof pages D, F), figs 1, 3, suppl. tables 1, 2.
Pugnatrypaea GMX.–Poore et al., 2019: 35, fig. 6j. 

Diagnosis.– Carapace with narrow triangular spiniform rostrum, low rounded shoulders lateral to eyestalks forming orbits; dorsal oval well defined. Eyestalk elongate, subrectangular, distomedial corner produced into rounded prominence, cornea poorly defined. Antennular peduncle much shorter than antennal. Second maxilliped small, narrow, straplike exopod carried closely against internal surface of endopod, distinctly shorter than endopodal merus. Third maxilliped lacking exopod, row of spiniform teeth forming distinct crista dentata on internal surface of ischium. Major chela with inferior keel of merus bearing proximal hooked spine or spined lobe, propodus external surface with multidenticulate lobe or tubercle extending over base of gape between fingers. Pleonal tergites mostly glossy smooth, enamel-like, first crossed by dorsal transverse furrows, broad oblique furrow on ventrally directed posterolateral lobe, second somite almost twice length of first. Male first and second pleopods uniramous, each composed of two articles, terminal article of first elongate, suboval, vestigial second male pleopod narrowly straplike. Female first and second pleopods biramous. Third through fifth pleopodal endopods each with short stubby appendix interna extending clearly beyond margin. Telson elongate subrectangular, posterior margin distinctly bilobate, lobes posteriorly separated by deep incision accommodating distinct median spine. Uropodal endopod broad, about 1.5 times longer than broad, dorsally with several stiff bristles distributed along longitudinal median ridge and posterolateral surface; exopod anterodorsal plate not reaching to distal endopod margin, elongate setae of exopod distal margin grading distomesially to dense line of heavy spiniform bristles. GenBank Accession numbers for paratypes, USNM 1541301 = ULLZ 6058: (16S) EU882915, (12S) EU875025, (H3) MN238262; USNM 1543631 = ULLZ 8279: (16S) EU992932, EU882933; (12S) EU87542, EU87543, (H3) MN238300.

Habitat.– Soft muds and silts (Fig. 4A, C, D), including those in immediate vicinity of hydrocarbon (methane) cold seeps, outer continental shelf and upper slope, 560 to at least 732 m depth. 

Distribution.– Western Atlantic Ocean, northwestern Gulf of Mexico, outer continental shelf off Louisiana and Texas. 

 Etymology.– The species name “emanata” is an adjective derived from the Latin “emanare”, meaning to ooze or flow out, alluding to the hydrocarbon seeps with which this species is often associated.

 Darryl L. Felder and Rafael Robles. 2020. A New Mud Shrimp of the Genus Pugnatrypaea from Outer Continental Shelf Waters of the northern Gulf of Mexico, commonly associated with Hydrocarbon Seeps (Crustacea: Decapoda: Callianassidae). Zootaxa. 4732(4); 545–555. DOI: 10.11646/zootaxa.4732.4.3