Socarnella delectabilis Hughes & Lowry, 2015, sp. nov.
Creators: name: Hughes, L. E.
name: Lowry, J. K.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Lysianassidae
Socarnella
Socarnella delectabilis

description: Socarnella delectabilis sp. nov. (Lys 161)
(Figs 4, 5)
Type material. Holotype male, 8.8 mm, dissected, 3 slides, AM P.69075, north-west of Port Hedland, North West Shelf, Western Australia, eastern Indian Ocean (19°59.0'S 117°51.4'E to 19°59.4'S 117°50.4'E), 42 m, epibenthic sled, 18 February 1983, FRV Soela (CSIRO stn NWS 01.B1.S); paratype male, AM P.69076, north-west of Port Hedland, North West Shelf, Western Australia, eastern Indian Ocean (19°28.6'S 118°55.0'E to 19°28.2'S 118°55.3'E), 39 m, epibenthic sled, 28 June 1983, FRV Soela (CSIRO stn NWS 03.B9.S); paratype male, AM P.69077, north-west of Port Hedland, North West Shelf, Western Australia, eastern Indian Ocean (19°29.6'S 118°52.2'E to 19°29.4'S 118°52.8'E), 38 m, epibenthic sled, 30 August 1983, FRV Soela (CSIRO stn NWS 04.B8.S).
Additional material examined. 2 specimens (1 female dissected, 3 slides and 1 male dissected, 4 slides), NMV J68198, between Port Hedland and Dampier, Northwest Shelf, Western Australia (19°58’00”S- 19°59’00”S 118°19’00”E- 118°18’00”E), 24 m, trawl, 1 June 1983, coll. Gary Poore & Helen Lew-Ton, RV Soela (NWA-2); 1?immature female, dissected, 3 slides, AM P.69079, north west end, McCluer Island, Northern Territory (11°02'S 132°58'E), 8 m, coral Acropora sp. bases at bommies, 16 October 1982, coll. P. Horner (NT-37); 1 juvenile, AM P.69080, south end of McCluer Island, Northern Territory (11°06'S 133°00'E), 8 m, coral Seriatopora hystrix, 17 October 1982, coll. J.K. Lowry (NT-61); 1 juvenile, AM P.69078, Lee Point, Darwin, Northern Territory (approx. 12°20’S 130°53’48”E), 1 m, old calcareous green alga Halimeda sp. on rock, 2 September 1984, coll. J. Just (NT- 111); 1 juvenile, NTM Cr. 010866, Orontes Reef, Port Essington, Northern Territory (11°4.5’S 132°4.8’E), 10 m, from coral Stylophora pistillata, 16 September 1985, coll. R. Williams (CP 177).
Type locality. North-west of Port Hedland, North West Shelf, Western Australia, eastern Indian Ocean (19°59.0'S 117°51.4'E to 19°59.4'S 117°50.4'E).
Etymology. Latin for delightful, agreeable.
Description. Holotype male, 8.8 mm, AM P.69075.
Head as deep as long; lateral cephalic lobe large, produced anteriorly; rostrum small; eyes subovate, black. Antenna 1 medium length, 0.3 × body; peduncular article 1 length 1.1 × width; article 2 length 0.5 × article 1; article 3 length 0.25 × article 1; accessory flagellum long, 0.6 × primary flagellum, 4-articulate, article 1 subequal to article 2 length; flagellum 6-articulate, callynophore absent, with posterodistal slender setae, without flagellar robust setae, calceoli absent. Antenna 2 subequal in length to antenna 1; peduncle with brush setae absent; article 3 short, 0.4 × article 4; peduncular articles 4–5 not enlarged; flagellum 5-articulate, calceoli absent. Labrum fused with epistome, produced away from posterior margin, rounded. Mandible incisors symmetrical, large, with convex margins; lacinia mobilis absent; accessory setal row without distal setal tuft, left and right rows each with 3 long, slender, multiserrate robust setae; molar developed as small, smooth setose flap; mandibular palp attached proximally, article 1 short, subequal to width; article 2 elongate, slender, length 4.1 × width, 1.8 × article 3, with 4 posterodistal A2-setae; article 3 slender, blade-like, long, length 3.1 × width, without A3-, B3- or D3- setae, with 3 apical E3-setae. Maxilla 1 inner plate narrow with 2 plumose apical seta; outer plate with 11 setalteeth in modified 6/5 arrangement; palp large, 2-articulate, with 6 short terminal conate setae and 1 long subterminal setae, distomedial margin serrate. Maxilla 2 inner and outer plates broad, subequal in length.
Maxilliped inner plate large, subrectangular, apically serrate, with 1 apical robust seta, oblique setal row reduced with 2 setae; outer plate small, subovate, without apical slender or robust setae, 10 vestigial medial robust setae; palp large, 4-articulate; article 2 length 2.8 × width, 1.4 × article 3; article 3 long, slender, length 2 × width; dactylus reduced, subtriangular without subterminal setae, unguis present.
Pereon. Gnathopod 1 simple; coxa large, 0.8 × coxa 2, anterior margin straight, anteroventral rounded, posterior margin straight; basis long, slender, length 2.5 × width, anterior margin smooth, with slender setae; ischium short, length 1.4 × width; merus, posterior margin with a few simple slender setae; carpus subrectangular, short, length 1.1 × width, 0.9 × propodus length, without denticulate patch near posterodistal margin; propodus, subrectangular, length 1.9 × width, tapering distally, posterior margin smooth, straight, posterior margin lined with short robust setae, without long robust setae, palm absent; dactylus weakly recurved, without subterminal spine. Gnathopod 2 subchelate; coxa large, 0.9 times coxa 3 length; ischium length 2.5 × width; carpus long, length 3 × width, posterior margin straight; propodus subovate, short, length 1.8 × width, palm subacute, excavate, 0.5 × propodus posterior margin, defined by posterodistal corner without robust setae; dactylus reaching corner of palm, posterior margin smooth. Pereopod 3 coxa large; merus weakly expanded anteriorly; merus and carpus posterior margin lined with slender setae; propodus with 3 long slender setae and 2 distal locking setae along posterior margin; dactylus weakly recurved. Pereopod 4 coxa deeper than wide, with large posteroventral lobe, anterior margin subquadrate, posterior margin straight; merus weakly expanded anteriorly; merus and carpus posterior margin lined with slender setae; propodus with 1 distal locking seta along posterior margin; dactylus weakly recurved. Pereopod 5 coxa equilobate; basis expanded with posterior margin smooth. Pereopod 6 coxa small, not lobate posteriorly; basis expanded posteriorly with posterior margin weakly concave, smooth; merus expanded; propodus with 1 distal locking seta; dactylus weakly recurved. Pereopod 7 basis expanded posteriorly, posterior margin weakly tapering distally, smooth, posteroventral corner rounded.
Pleon. Pleonites 1–3 dorsally smooth. Epimeron 1–2 subquadrate. Epimeron 3 broadly rounded. Urosomites 1–3 dorsally smooth. Uropod 1 without long fine setae; peduncle with 7 dorsolateral and 2 apicomedial robust setae; outer ramus subequal to inner ramus length; outer ramus with 4 lateral robust seta; inner ramus with 2 robust setae. Uropod 2 without fine setae; peduncle with 1 dorsolateral and 2 apicomedial robust setae; rami subequal in length, outer ramus with 4 dorsal robust setae; inner ramus with 1 robust setae, without constriction. Uropod 3 peduncle long, length 2 × width, with 3 robust setae, without dorsolateral flange; rami lanceolate, inner ramus reduced, 0.7 × outer ramus; outer ramus 1-articulate; outer ramus with 1 dorsolateral robust seta, inner rami without robust setae. Telson length 1.4 × width, cleft (40%), lobes divergent, with 2 apical robust setae, 2 short dorsal slender setae, and 2 marginal penicillate setae.
Remarks. Socarnella delectabilis sp. nov. has a 4-articluate accessory flagellum on antenna 1 and a 40% cleft in the telson while S. bonnieri and S. cavipalmata both have a 5-articulate accessory flagellum and a telson which is apically notched to only 10%. Socarnella delectabilis is most similar to S. cavipalmata with both species having subacute gnathopod 2 propodus with an excavate palm while in S. bonnieri the palm is parachelate and entire. The palm margin is 50% of the propodus posterior margin in S. delectabilis with the propodus 1.8 times as long as broad, while in S. cavipalmata the palm is only 33% with a much longer propodus, being 2.5 times as long as broad.
Distribution. Western Australia: North West Shelf. Northern Territory: Port Essington, Lee Point and McCluer Island (current study).
description: Published as part of Hughes, L. E. & Lowry, J. K., 2015, Two new species of Lysianassidae Dana, 1849 from Australia: Riwo zeidleri and Socarnella delectabilis (Crustacea: Peracarida: Amphipoda) in Zootaxa 3936 (1), DOI: 10.11646/zootaxa.3936.1.4, http://zenodo.org/record/244435