Valettiopsis minuta, Horton, 2004

Horton, Tammy, 2004, Revision of the amphipod genus Valettiopsis Holmes, 1908 (Crustacea: Lysianassoidea), with the addition of three new species, Journal of Natural History 38 (14), pp. 1735-1755 : 1749-1753

publication ID	https://doi.org/ 10.1080/0022293031000156259
persistent identifier	https://treatment.plazi.org/id/03ED87D2-FFFD-FF98-17C7-FF7B94836105
treatment provided by	Felipe
scientific name	Valettiopsis minuta
status	sp. nov.

Treatment

Valettiopsis minuta View in CoL sp. nov.

( figures 9–11 View FIG View FIG View FIG )

Type material. Holotype adult female, dissected specimen and slide series. USNM reg. no. 261212.

Type locality. South Carolina, North Atlantic Ocean (32 ‡ 44 ’ N, 78 ‡ 06 ’ W; 194–212 m) .

Material examined. South Carolina, North Atlantic Ocean (32 ‡ 44 ’ N, 78 ‡ 06 ’ W; 1983, 194– 212 m; traps 1–6), holotype female, 11.1 mm, USNM reg. no. 261212 .

South Carolina, North Atlantic Ocean (32 ‡ 44 ’ N, 78 ‡ 06 ’ W; 1983, 194– 212 m; traps 1–6), paratypes four female specimens, 9.4, 10.3, 11.1 and 12 mm, nine male specimens, 9.6–10.3 mm, 26 juvenile specimens, v 8.6 mm, additional parts of w 12 specimens, USNM reg. no. 1009938 .

Florida , south of Tortugas, 23 July 1932, 83–91 fathoms (152–166 m), three female specimens, 9.8–11.1 mm, USNM reg. no. 1009939 .

Description. Holotype female, 11.1 mm. Head and body: colour tan, without setae. Head: exposed, deeper than long; lateral cephalic lobe broadly rounded with shallow excavation for antenna 2; eyes absent. Pereonites and pleonites: dorsally smooth. Urosomites: 1–3 free; urosomite 1 produced into prominent dorsal tooth, strongly curved, apex acute.

Antenna 1: medium length; peduncle article 1 longer than wide; article 2 short (0.3 6 length of article 1); article 3 medium (0.25 6 length of article 1); flagellum with 20–22 articles; callynophore strong, setae present on flagellar articles; accessory flagellum well developed with six articles, short (0.2 6 primary flagellum); article 1 at least twice as long as article 2.

Antenna 2: slightly longer than antenna 1; peduncle without brush setae in female, weak in male; article 3 short (0.4 6 article 4); article 4 enlarged; article 5 subequal in length to article 4 but more slender; flagellum well developed with 22–24 articles.

Mouthparts: forming subquadrate bundle. Upper lip: rounded. Lower lip: outer lobes elongate, robustly spinulose on inner distal margin.

Mandible: incisor robustly seven-dentate, lacinia mobilis six-dentate; eight accessory setae, interspersed with long plumose intermediate setae. Molar with strong triturating surface, large plumose seta present. Palp attached level with molar, article 1 short, without setae; article 2 elongate, broadened medially/ centrally, D2 setae along distal half; article three oval and rounded distally, with three A3 setae, three E3 setae and 25 D3 setae on the distal two-thirds of the margin.

Maxilla 1: inner plate tapering distally, inner margin fully setose. Outer plate setal teeth in 7:4 arrangement. Outer row: ST1–3 large, stout, with cusps; ST4–5 large, slender, with cusps; ST6–7 small, slender, cuspidate, ST6 slightly displaced from ST5, ST7 slightly displaced from ST6. Inner row: STA large slender, fivecuspidate; STB–C large, slender, seven-cuspidate; STC displaced from STB; STD large, slender, five-cuspidate, displaced from STC. Palp: two-articulate with 10 terminal robust setae and six subterminal setae; article 1 with one long submarginal lateral spine.

Maxilla 2: inner and outer plates narrow, subequal in length, densely setose; inner plate with row of pappose facial setae.

Maxilliped: inner plate subrectangular, 0.62 6 outer plate, with 12 long apical setae; three distal nodular setae on apical face near inner margin; oblique setal row with 15 long plumose setae and three submarginal setae. Outer plate small, reaching halfway along palp article 2, subovate, medial margin finely setose; 13 short robust setae proximally on the inner margin grading to six elongate plumose robust setae distally; submarginal inner margin with horizontal rows of two to three short fine setae. Palp large, elongate and four-articulate; inner margin of article 2 with distal row of long robust setae; article 3 with row of nine strong facial setae and two groups of medial lateral setae; dactylus well developed with one subterminal spine and one fine seta. Each article of the palp with outer apical margin bearing long robust setae.

Coxae 1–3: without setae along ventrolateral margin.

Gnathopod 1: subchelate; coxa 1 reduced, subtriangular, three-quarters length of coxa 2, tapering distally with four setae on distal margin; basis long (length 4.2 6 breadth); ischium short (length 1.5 6 breadth); merus short (length 1.15 6 breadth) with patch of short setules on posterior margin; carpus short (length 1.67 6 breadth) subtriangular, posterior margin with long setae, five of which are distally dentate; propodus large, subrectangular (length 2 6 breadth), longer than carpus, posterior margin smooth, straight, with five groups of simple slender setae; seven groups of distomedial setae; palm nearly transverse, slightly concave, lined with a row of short slender setae and with four long robust setae on the posterodistal corner; dactylus simple with one long medial seta and one robust seta on posterior margin.

Gnathopod 2: subchelate; coxa large, expanded distally and subequal to coxa 3, with five submarginal setae distally, and one on anterodistal corner; basis long (length 5 6 breadth); ischium long (length 2.7 6 breadth); merus short (length 1.8 6 breadth); carpus subtriangular (length 2.6 6 breadth), longer than propodus, with 10 groups of long simple setae; propodus long, subrectangular (length 2 6 breadth) with seven groups of long simple setae on posterior margin, posterodistal margin with a row of four robust setae decreasing in size, and three serrate setae; palm nearly transverse, straight, lined with a row of short robust setae and with one long simple seta proximal to the dactylus; dactylus not reaching palmar angle; posterior margin smooth with one long medial seta and one spine on posterior margin.

Pereopod 3: simple, coxa large, subrectangular; propodus longer than carpus; carpus with five groups of robust setae and one robust seta (locking spine) along posterior margin; dactylus curved with one seta on posterior margin.

Pereopod 4: simple, coxa deeper than wide, posteroventral lobe weak with both anterior and posterior margins rounded; propodus with four groups of robust setae along posterior margin; dactylus curved, with one seta on posterior margin.

Pereopod 5: coxa bilobate, anterior lobe slightly produced ventrally, smooth posterior margin with one robust seta; basis expanded (length 1.25 6 width); propodus with three groups of robust setae and one robust seta (locking spine) along anterior margin; dactyl long and curved with one seta on posterior margin.

Pereopod 6: longer than pereopod 5 with coxa weakly equilobate and posterodistal lobe of basis weaker than pereopod 5.

Pereopod 7: shorter than pereopod 6 with coxa reduced, bilobate, posterior lobe slightly produced ventrally, basis more broadly expanded and tapered.

Epimeron 1, anteroventral corner rounded with one seta; epimeron 2, posteroventral corner produced into small tooth, two setae on ventral margin; epimeron 3, posteroventral corner produced into a small, acute tooth, four to five setae on ventral margin.

Uropod 1: biramous, inner and outer rami subequal with lateral and medial rows of short robust setae; peduncle with rows of short setae on inner and outer margins, one large robust seta on peduncle at base of outer ramus.

Uropod 2: biramous, as uropod 1 but shorter and with fewer peduncle setae.

Uropod 3: biramous, well developed, peduncle long (length 1.5 6 breadth), with apicolateral robust setae; rami lanceolate, subequal in length, with lateral and medial rows of short robust setae; outer ramus two-articulate, article 2 short; inner edge of inner ramus with slender plumose setae (may be difficult to see).

Telson: cleft for 78% of length; outer margins with one pair of robust setae laterally; lobes notched apically with two graduated robust setae, and one fine seta; inner distal margin produced into sub-acute apex.

Remarks. Valettiopsis minuta is one of the smallest species in the genus and strongly resembles V. lincolni , especially in the form of the gnathopods. It is distinguished from that species in having a distinctly curved upper margin of the dorsal tooth on urosomite 1 (compared with the weakly sinuous upper margin of the dorsal tooth on urosomite 1 in Valettiopsis lincolni ), more rounded posterior expansion of the basis of pereopods 5–7, and fewer articles in the antenna 1 flagellum (20–22 versus 27–30).

Etymology. This species is named in reference to its small size in comparison with other Valettiopsis species.

Valettiopsis multidentata Barnard, 1961 View in CoL

Valettiopsis multidentatus Barnard, 1961: 53 , figure 23.

Valettiopsis multidentata: Lincoln and Thurston, 1983: 87–89 View in CoL .

Type material. Female specimen, 18 mm.

Type locality. Kermadec Trench, Station 665, 36 ‡ 38 ’ S, 178 ‡ 21 ’ E; 2470 m, grey clay, HOT, 25 February 1952.

Distribution. Only known from the type locality.

Remarks. This species is easily distinguished from the other members of the genus in having pereon segments 5–7 and pleon segments 1–3 dentate dorsally, in addition to the typical acute dorsal tooth on urosome 1.

Valettiopsis ruffoi Serejo and Wakabara, 2003

Valettiopsis ruffoi Serejo and Wakabara, 2003 : figures 2–4 View FIG View FIG View FIG .

Type material. Holotype female specimen, 25 mm, reg. no. 15697; paratype male specimen, 25.3 mm, reg. no. 15698, Museu Nacional , Rio de Janeiro.

Type locality. TAAF MD 55 /Brazil, 1987, Marion Dufresne cruise, station 45, 19 ‡ 01 ’ S, 37 ‡ 47 ’ W ; 1500–1575 m.

Distribution. Only known from the type locality.

Remarks. Valettiopsis ruffoi resembles V. dentata and V. longidactyla in having slender, elongate gnathopods 1 and 2 with the carpus distinctly longer than the propodus. It can be distinguished easily from these species, and from the other members of the genus by the strongly oblique palms on gnathopods 1 and 2, the strong posteroventral lobe on coxa 4, reduced dorsal tooth on urosomite 1, and very short distal article of uropod 3 outer ramus (1/13 of proximal article).