Parakanthophoreus Larsen & Araújo-Silva, 2014, gen. nov.

Genus Parakanthophoreus gen. nov.

Diagnosis. Pleonite 5 without ventral spur. Pleotelson without lateral spines. Cheliped carpus, propodus, and fixed finger without extensive surface ornamentation; fixed finger without proximal inner denticulations. Uropod basal article without accessory spur; uropod endopod article 1 without spur.

Type species ( by original designation, ICZN article 67b). Parakanthophoreus greenwichius sp. nov.

Etymology. The genus name reflects the close and intermediate relationship with both Paraleptognathia and Akanthophoreus.

Gender. Masculine.

Remarks. The new genus is easily separated from its ‘parent taxa’- by the lack of pleotelson spurs, lack of cheliped carpal/propodal ornamentation, and lack of proximal fixed finger denticulation.

Species included. See Table 1; mandatory spelling changes have been performed in according with the ICZN article 34.

Parakanthophoreus greenwichius sp. nov. (Figs 8–10)

Material examined. Holotype: female, ANDEEP-SYSTCO, DZMB-HH 1360, station 24, 52°01.98' S, 00°01.12'W (southwest of Buvetøya Island), 2997.9 meters, 0 6 Dec 2007, EBS-epi. (Zmh k-44138). Paratypes: One female, same locality, dissected (ZMH K- 44139). Two non-ovigerous females, ANDEEP-SYSTCO, DZMB- HH 10540, station 85, 52°01.54'S, 00°00.22'E, 2987.4 meters, 18 Feb 2002, EBS-epi (ZMH K- 44140, one specimen processed for DNA analysis).

Diagnosis. Female. Cephalothorax shorter than pereonites 1 and 2 combined. Antennule article 1 much shorter than rest of antennule; article 4 with apical setae with wide basis. Maxilliped basis without long setae; endites with robust outer seta. Cheliped merus without ventral process; carpus with huge carpal shield; propodus and dactylus without crenulations; fixed finger with heavy, medially-serrated ventral setae.

(*)Probably represents a separate (and new) genus, but without the maxilla it is impossible to determine with certainty.

Etymology. Named after the Greenwich median (adjectival) as the longitude of the type locality.

Description. Female. Body from holotype, appendages from dissected paratype.

Body (Fig. 8 A, B) elongate, 2.0 mm long, about eight times as long as wide. Cephalothorax shorter than pereonites 1 and 2 combined. Pereonites all wider than long. Pleon short (length including pleotelson about 20% of total body length). All pleonites subequal in length and width. Pleotelson longer than two last pleonites combined, widening medially, apex rounded, with two pairs of terminal setae.

Antennule (Fig. 9 A) shorter than cephalothorax, with partly fused terminal cap-like article. Article 1 much shorter than other articles combined, very stout (l/w ratio 1.3), with two setulose medial setae, one simple and one setulose distal setae. Article 2 only marginally shorter than article 1, with two simple distal setae and three setulose distal setae. Article 3 only half as long as article 2, apparently naked. Article 4 almost twice as long as article 3, with two long thick, and two short simple distal setae. Terminal cap-like article partly fused with article 4, with two long, thick, and one small simple distal, setae.

Antenna (Fig. 9 B) 0.75 times as long as antennule. Article 1 broken. Article 2 shorter than article 5, with numerous proximal setules and one dorsodistal simple seta. Article 3 shorter than article 2, with one dorsodistal simple seta. Article 4 longer than other articles, with fusion line, with one subdistal setulose seta at each margin, and three simple distal setae of which two are longer than article 5. Article 5 less than half as long as article 4, with one long distal seta. Article 6, with three distal simple setae.

Mouthparts (Fig. 9 C–J). Labrum (Fig. 9 C) with finely setose, rounded apical margin. Mandibles (Fig. 9 D, E) molar process tapering distally, longer than incisor, with distal spines. Right mandible (Fig. 9 D) incisor with four weakly defined denticles. Left mandible (Fig. 9 E) lacinia mobilis blunt, as long as incisor; incisor with three weakly defined denticles. Labium (Fig. 9 F) consisting of one pair of weakly setose lobes, with lateral extensions (possibly a rudiment of a second pair of lobes). Maxillule (Fig. 9 G) endite with seven apical spiniform setae, which one is serrated, shaft with several small setules on outer margins; palp broken. Maxilla (Fig. 9 H) large (almost as large as mandible), widest at base, with evenly spaced setules. Maxilliped (Fig. 9 I) basis without setae; endites narrower than basis, not fused, each with inner (apparently articulated) denticles and outer robust seta and outer depression with small spines/setules. Palp article 1 naked; article 2 with one simple seta on outer margin, one serrated, and two thick setae on inner margin; article 3 with two long thick and two short thin inner setae; article 4 only half times as wide as article 3, with four long, thick inner and two subdistal thinner outer simple setae. Epignath (Fig. 9 J) slender and naked.

Cheliped (Fig. 8 C) with basis unequally divided by long, prominent sclerite, shorter than carpus, with one dorsodistal simple setae. Merus triangular, with one ventromedial seta. Carpus as long as propodus (including fixed finger), widest distally, with two ventromedial seta and one small dorsal seta at each end, carpal shield prominent. Propodus robust (l/w ratio 1.7), dorsal crest low and without crenulations, with simple seta at dactylus insertion but apparently without row of inner setae (possibly an artefact). Fixed finger with two very thick, weakly serrated ventral setae and three thick, simple setae on inner margin, inner margin heavily chitinized but with only two gently curved denticles. Dactylus robust, as long as fixed finger, without crenulations or setae.

Pereopod 1 (Fig. 10 A) coxa with one simple seta. Basis longer than three succeeding articles combined and wider than that of pereopods 4–6 (l/w ratio 2.3), naked. Ischium with one ventral seta. Merus as long as carpus, widening distally, with one long, spiniform seta and one simple seta ventrodistally. Carpus 0.65 times as long as propodus, with two long, spiniform distal setae. Propodus more than half as long as basis, with ventral margin with numerous small spines, two ventrodistal spiniform setae and one spine both dorso- and ventro-distally, with small simple dorsodistal seta. Dactylus naked, about as long as unguis, combined half as long as propodus.

Pereopod 2 (Fig. 10 B) as pereopod 1 except: basis with one long and small setulose dorsoproximal setae. Carpus with three spiniform distal setae.

Pereopod 3 (Fig. 10 C) as pereopod 2.

Pereopod 4 (Fig. 10 D) coxa fused to body. Basis more slender than those of pereopods 1–3 (l/w ratio 2.6), with two dorsomedial setulated setae. Ischium with two setae. Merus shorter than carpus, widening distally, with two short, spiniform ventrodistal setae. Carpus only slightly shorter than propodus with three spiniform setae and one “bone-shaped” distal seta. Propodus with one spine and one spiniform seta dorsodistally, two ventrodistal spiniform setae and small ventral spines. Dactylus shorter than propodus, with two distal spines and two rows of small ventral spines; unguis clearly demarcated, less than half as long as dactylus.

Pereopod 5 (Fig. 10 E) as pereopod 4 (dactylus broken).

Pereopod 6 (Fig. 10 F) as pereopod 4 except: dactylus with distal simple seta.

Pleopods (Fig. 8 D) subequal. Endopod with one inner and twelve plumose outer setae. Exopod basal seta arising from incompletely fused rudimentary article and separated from other setae, with ten plumose outer setae of which the most distal is shorter and thicker than the adjacent ones.

Uropod (Fig. 8 E) longer than pleotelson. Basal article longer than exopod, naked. Endopod with two subequal [length] articles; article 1 with six simple distal and one setulated setae; article 2 with one simple seta, rest of setation broken. Exopod with two subequal [length] articles, half as long as first endopod article; article 1 naked; article 2 with one thick and one simple distal seta.

Remarks. This species can be separated from all other species of Parakanthophoreus by the heavy, medially serrated, ventral setae on the cheliped fixed finger. In addition, the short and thick antennules, the huge carpal shield, and the robust maxilliped setae, set this species apart from other recorded species of the genus except the Arctic species P. inermis (Hansen, 1913) which cannot possibly be present in the Antarctic.