Hemilamprops impellucidus n. sp.

(Figs 23–28)

Hemilamprops pellucida . Jones, 1960: 9–11.— Jones, 1963: 52–53.

Type material. Holotype: ovigerous female, NIWA 93204, 42.782°S, 176.70– 176.72°E, 1023–1026 m, 16 April 2007 . Paratypes: ovigerous female, dissected, NIWA 94873, collected with holotype; female, NIWA 94879, collected with holotype; adult male, dissected, NIWA 93190, 43.52°S, 178.62°E, 424–425, 18 April 2007 .

Other material. 3 individuals, NIWA 12773, 45.35°S, 171.95°E, 1225 m, 13 October 1965. 2 inviduals, NIWA 12774, 45.2°S, 171.87°E, 860 m, 13 October 1965 . 14 individuals, NIWA 45798, 44.561 – 44.559 °S, 178.48°W, 1076–1103 m, 10 April 2007 . 3 individuals, NIWA 95396; 4 individuals, NIWA 95398, 2 individuals, NIWA 95403, 44.486 – 44.484 °S, 177.141– 177.146°E, 1235–1239 m, 6 April 2007. 1 individual, NIWA 95392, 3 individuals, NIWA 95401, 44.016 – 44.014 °S, 178.521– 178.518°E, 769–771 m, 7 April 2007. 20 individuals, NIWA 95405; 5 individuals, NIWA 95393; 7 individuals, 95401, 43.979 – 43.985 °S, 179.63– 179.622°E, 529–530 m, 9 April 2007. 7 individuals, NIWA 95401, 43.799 – 43.805 °S, 175.316– 175.315°E, 418–422 m, 27 April 2007. 1 individual, NIWA 12566, 43.583°S, 176.06°W, 229 m, 7 February 1954 . 40 individuals, NIWA 45720, 43.53 – 43.536°S, 178.505– 178.512°E, 346 m, 24 April 2007. 1 individual, NIWA 93190; 5 individuals, NIWA 95395, 43.521 – 43.523 °S, 178.62– 178.63°W, 424–425 m, 18 April 2007. 100 individuals, NIWA 95399, 43.512 – 43.52°S, 176.18°W, 196–218 m, 14 April 2007 . 11 individuals, NIWA 45796, 43.29 – 43.293°S, 175.55– 175.56°W, 638–644 m, 14 April 2007. 4 individuals, NIWA 95397, 43.065 – 43.073 °S, 174.93°W, 933–940 m, 13 April 2007 . 30 individuals, NIWA 45797; 6 individuals, NIWA 95394, 42.996 – 42.991 °S, 178.996– 179.005°E, 520–530 m, 24 April 2007. 2 individuals, NIWA 12568, 42.898°S, 170.303°E, 245 m, 19 February 1982 . 2 individuals, NIWA 12567, 42.84°S, 169.978°E, 297 m. 60 individuals, NIWA 45799, 42.782°S, 176.72°W, 1023–1026 m, 16 April 2007 . 10 individuals, NIWA 95400, 42.621 – 42.62°S, 175.923– 175.934°E, 1194–1199 m, 26 April 2007. 1 individual, NIWA 12569, 42.39°S, 170.893°E, 167 m, 30 March 1982 . 1 individual, NIWA 12771, 41.377°S, 170.902°E, 285 m, 24 February 1982 . 3 individuals, NIWA 12772, 40.88°S, 171.413°E, 195 m, 6 March 1982 . 12 individuals, NIWA 45794, 40.88 – 40.888°S, 170.856– 170.857°E, 529–534 m, 6 June 2007. 4 individuals, NIWA 95404, 39.637 – 39.646 °S, 172.153– 172.152°E, 264–266 m, 7 June 2007. 1 individual, NIWA 94878, 38.618 –- 38.626°S, 168.943– 168.949°E, 480–482 m, 29 May 2007.

Diagnosis. Female carapace without lateral ridges, without setae, dorsal crest serrate, continuing onto eyelobe. Telson 0.9 uropod peduncles, with 9 pairs lateral setae, 3 terminal setae, central seta longest. Adult male carapace dorsal crest entire. Telson equal to uropod peduncles, with 8–10 pairs lateral setae, 3 unequal terminal setae, central seta longest. Uropod exopod article 1 0.9 legnth of article 2.

Description. Holotype ovigerous female, NIWA 93204; paratype ovigerous female, NIWA 94873.

Ovigerous female, holotype 7.6 mm, paratype 8.2 mm. Carapace without lateral ridges, with distinct dorsolateral swelling anteroventral corner serrate, medial dorsal crest serrate; pseudorostral lobes 0.3 carapace length, meet in front of eyelobe; eyelobe 0.1 carapace length, with distinct lenses; carapace 1.4–1.5 length of pereonites together (Fig. 23A, B).

Antennule peduncle article 1 1.3 times articles 2 and 3 together, margin serrate, with simple setae; article 2 0.5 article 1 length, with few simple setae; article 3 0.6 article 2 length, unarmed; main flagellum of 5 articles, 0.9 length of article 1, with 2 simple and 2 aesthetasc setae terminally; accessory flagellum broken off (Fig. 23C).

Antenna of 4 articles; article 1 stout, with 1 pappose and 1 plumose setae; article 2 small, with pappose seta; article 3 margins serrate; article 4 slender, equal to article 3 length, with few simple setae terminally (Fig. 23D).

Mandible navicular, with 12–14 microserrate setae medially, lacinia mobilis with 3 cusps (Fig. 23E).

Maxillule with 2 endites; outer endite with 1 microserrate and 2 rows stout setae terminally; inner endite with 3 simple and 1 tricuspic setae; palp with 2 setae (Fig. 23F).

Maxilla with 3 endites; broad endite; medial narrow endite with microserrate setae terminally; distal narrow endite with microserrate setae terminally; both narrow endites (Fig. 23G).

Maxilliped 1 basis produced distally as broad lobe, distal margin with stout seta, with 4 pappose setae medially; ischium absent; merus with 1 plumose seta laterally; carpus 1.9 merus length, medial face with pappose and 4 comb setaes, with 2 plumose setae laterally; propodus 0.4 carpus length, margin serrate, with 2 plumose and several simple setae; dactylus 1.0 propodus length, with simple setae terminally (Fig. 23H).

Maxilliped 2 basis 0.8 all other articles together, with 5 thickly plumose and 1 plumose setae, brood plate with stout annulate setae; ischium 0.1 basis length, uanrmed; merus 2.7 ischium length, with thickly plumose seta medially, plumose seta laterally; carpus 1.5 merus length, with plumose setae medially, plumose seta laterally; propodus 0.8 carpus length, with sparsely plumose setae medially, plumose seta laterally; dactylus 0.5 propodus length, with 3 simple setae terminally (Fig. 24A).

Maxilliped 3 basis 1.1 all other articles together, with plumose setae medially, distal corner with 1 plumose and 2 pappose setae; ischium 0.08 basis length, unarmed; merus 1.3 ischium length, with 3 pappose setae medially, 2 plumose setae laterally, lateral margin with few small teeth; carpus 3.1 merus length, with pappose setae medially, plumose setae laterally; propodus 0.8 carpus length, with plumose setae medially and laterally; dactylus 0.3 propodus length, with 4 simple setae terminally; exopod 0.8 basis length, basal article with 2 plumose setae, flagellum with plumo-annulate setae (Fig. 24B).

Pereopod 1 basis 0.9 next 4 articles together, with pappose setae on margins; ischium 0.1 basis length, with plumose seta; merus 2.3 ischium length, with 2 plumose and 3 simple setae; carpus 1.0 merus length, with 4 simple setae; propodus 2.2 carpus length, with several simple setae; dactylus broken; exopod 0.7 basis length, basal article with 4 simple setae, flagellum with plumo-annulate setae (Fig. 24C).

Pereopod 2 basis 0.7 all other articles together, with plumose and simple setae; ischium 0.1 basis length, with 2 setae with single subterminal setule; merus 2.6 ischium length, with 2 setae with single subterminal setule and 4 plumose setae; carpus 2.3 merus length, with 13 setae with single subterminal setule and 4 simple setae; propodus 0.2 carpus length, with seta with single subterminal setule; dactylus 2.6 propodus length, with 4 setae with single subterminal setule and 5 simple setae terminally; exopod 0.8 basis length, basal article with plumose seta, flagellum with plumo-annulate setae (Fig. 24D).

Pereopod 3 basis 1.3 all other articles together estimated, with 6 plumose setae; ischium 0.1 basis length, with 2 simple setae; merus 1.2 ischium length, with 4 annulate setae; carpus 2.3 merus length, with 6 annulate setae; propodus 0.4 carpus length, with annulate seta; dactylus 0.6 propodus length, with simple seta terminally; exopod rudimentary, 0.1 basis length, of 2 articles with 3 simple setae (Fig. 24E).

Pereopod 4 not figured.

Pereopod 5 basis broken, with plumose setae; ischium with 1 simple and 2 annulate setae; merus 1.4 ischium length, with 3 annulate setae; carpus 1.6 merus length, with 7 annulate setae; propodus 0.5 carpus length, with annulate seta; dactylus 0.5 propodus length, with 2 simple setae and simple seta terminally (Fig. 24F).

Telson 1.7 length of pleonite 6, with 9 pairs microserrate setae with single subterminal setule laterally, 3 terminal setae, central seta stout and longest (Fig. 25).

Uropod peduncles 1.8 pleonite 6 length, 1.1 telson length, with 13–15 setae with single subterminal setule medially. Uropod endopod broken; article 1 broken, medial margin with hyaline fringe, with setae with single subterminal setule medially, simpe setae laterally. Uropod exopod broken (Fig. 25).

Paratype adult male, NIWA 93190 .

Adult male, 7.2 mm. Carapace with lateral ridges, with dorsolateral swellings, medial crest entire; pseudorostral lobes 0.4 carapace length; eyelobe 0.1 carapace length, with multiple lenses; carapace 1.3 length of pereonites together (Fig. 26A, B).

Antennule peduncle article 1 1.4 articles 2 and 3 together, with 3 simple setae; article 2 0.5 article 3 length, with simple seta; article 3 0.5 article 2 length, unarmed; main flagellum of 5 articles, article 1 with many slender aesthetascs, 2 stout aesthetascs terminally; accessory flagellum of 3 articles, with few simple setae (Fig. 26C).

Antenna broken, expected to extend past pereon; peduncle of 5 articles; article 2 with pappose seta; articles 4– 5 with ranks of setae, completely circling articles; flagellum broken, articles each with several setae (Fig. 26D)

Mandible–maxilliped 2 not figured.

Maxilliped 3 basis 1.3 all other articles together, with pappose setae medially, simple setae laterally, with 4 plumose setae at distal corner; ischium 0.06 basis length, unarmed; merus 2.0 ischium length, with pappose setae medially, plumose setae laterally; carpus 1.9 merus length, with pappose setae medially, plumose setae laterally; propodus 1.0 carpus length, with plumose setae medially and laterally; dactylus 0.3 propodus length, with 3 simple setae terminally; exopod 0.8 basis length, basal article with many short plumose setae, flagellum with plumoannulate setae (Fig. 27A).

Pereopod 1 basis 0.7 all other articles together, with pappose seate medially, plumose setae laterally; ischium 0.06 basis length, with 2 plumose setae; merus 2.8 ischium length, with plumose setae on margins; carpus 1.4 merus length, with 2 simple and 1 plumose setae; propodus 1.9 carpus length, with 4 simple setae; dactylus 1.0 propodus length, with 6 simple setae and 3 simple setae terminally; exopod 0.7 basis length, basal article with many short plumose setae, flagellum with plumo-annulate setae (Fig. 27B).

Pereopod 2 basis 1.0 next 4 articles together, with pappose setae medially, plumose setae laterally; ischium 0.1 basis length, with seta with single subterminal setule; merus 2.0 ischium length, with 2 simple, 1 plumose and 1 with single subterminal setule setae; carpus 2.9 merus length, with 9 microserrate, 4 simple and 1 plumose setae; propodus 0.2 carpus length, with simple seta; dactylus broken off; exopod 0.9 basis length, basal article with many short plumose setae, flagellum with plumo-annulate setae (Fig. 27C).

Pereopod 3 basis 0.5 all other articles together, with many plumose setae; ischium 0.06 basis length, with 2 annulate setae; merus 2.7 ischium length, with 3 simple setae; carpus 1.1 merus length, with 2 simple, 2 plumose and 2 annulate setae; propodus 0.7 carpus length, with annulate seta; dactylus 0.3 propodus length, with simple seta and simple seta terminally; exopod 0.9 basis length, basal article with several plumose setae, flagellum with plumoannulate setae (Fig. 27D).

Pereopod 4 basis 0.6 all other articles together, with pappose and plumose setae; ischium 0.07 basis length, with 2 simple and 4 annulate setae; merus 2.3 ischium length, with 1 simple and 2 annulate setae; carpus 1.1 merus length, with 2 simple, 2 plumose and 4 annulate setae; propodus 0.6 carpus length, with annulate seta; dactylus 0.6 propodus length, with simple seta and simple seta terminally; exopod 0.9 basis length, basal article with several plumose setae, flagellum with plumo-annulate setae (Fig. 27E).

Pereopod 5 basis broken, with plumose and simple setae; ischium with 1 plumose and 3 annulate setae; merus 2.7 ischium length, with 2 plumose setae; carpus 1.1 merus length, with 1 plumose, 1 simple and 4 annulate setae; propodus 0.6 carpus length, with annulate seta; dactylus 0.6 propodus length, with simple seta terminally (Fig. 27F).

Telson 2.6 length of pleonite 6, with 8–9 simple lateral setae, 3 terminal setae, central seta more than twice length of outer pair (Fig. 28).

Uropod peduncles 2.7 pleonite 6 length, 1.0 telson length, with many simple setae medially, 4 distal most medial setae microserrate. Uropod endopod broken; article 1 with 13–15 setae with single subterminal setule medially, several simple setae laterally; article 2 0.8 article 1 length, with 3–4 setae with single subterminal setule medially, 3 simple setae laterally; article 3 missing. Uropod exopod article 1 with 4 simple setae; article 2 1.1 article 1 length, with 10 simple setae marginally, 2 simple setae terminally (Fig. 28).

Etymology. The new species is named impellucidus from the Latin im, meaning not, in combination with pellucidus, as it is most likely to be confused with Hemilamprops pellucidus .

Depth. 167–1239 m.

Distribution. Chatham Rise, Challenger Plateau, New Zealand, 38.618– 45.35°S, 168.943°E– 178.62°W.

Remarks. Hemilamprops impellucidus is most likely to be confused with H. pellucidus, as the species share an overall similarity in form and the serrate dorsal crest. However, in H. impellucidus the antennule main flagellum is of five long, slender articles, the eyelobe has lenses in both females and males, the telson is similar in length to the uropod peduncles (0.9 in the female, 1.0 in the male), and the telson terminal setae are distinctly unequal, with the central seta longer than the outer pair. In contrast, in H. pellucidus, the antennule main flagellum is of four short, stout articles, the eyelobe is without lenses in either sex, the telson is much less than 0.9 the length of the uropod peduncles, and the telson terminal setae are equal in length. In addition, reproductive individuals of H. impellucidus are 7–8.5 mm, while very immature males and females of H. pellucidus are 6–8 mm, suggesting mature individuals will likely be distinctly larger than mature individuals of H. impellucidus .