Valettiopsis concava, Hendrycks, Ed A., 2007

Hendrycks, Ed A., 2007, A new species of Valettiopsis Holmes, 1908 (Crustacea: Gammaridea: Lysianassoidea) from abyssal waters off California, Zootaxa 1501, pp. 45-56 : 47-55

publication ID	https://doi.org/ 10.5281/zenodo.177103
DOI	https://doi.org/10.5281/zenodo.6237355
persistent identifier	https://treatment.plazi.org/id/847B4015-AB34-F338-66A6-CD1DFDDAFEFE
treatment provided by	Plazi
scientific name	Valettiopsis concava
status	sp. nov.

Treatment

Valettiopsis concava sp. nov.

( Figures 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Valettiopsis sp.— Beaulieu 2001: 810, table 4.

Type material. HOLOTYPE: adult female, 12 mm, (appendages on one slide), CMNC 2007-0002, Pulse 25, Station M, ALVIN Dive 2920, taken from Hyalonema sp., stalk # 33, 34° 45' N; 123° 00' W, ~ 220 km west of Point Conception, California, 4100 m, 30 April 1995, collector Stace E. Beaulieu. ALLOTYPE: adult male, 13.1 mm, (appendages on one slide), CMNC 2007-0003, dive/sample T421-A8, taken by ROV Tiburon from ship Western Flyer, baited trap, 36° 42' 22.78" N; 123° 31' 43.27" W, near Monterey Bay, California, 3607 m, 1 May 2002, collector James P. Barry. PARATYPES: CMNC 2007-0004, 1 female, 3 males, dive/sample T421-A8, other data same as allotype above; CMNC 2007-0005, 12 females, 24 males, dive/sample T421-A6, other data as above; CMNC 2007-0006, 17 females, 17 males, dive/sample T421-A5, other data same as above; USNM-1101918, 1 female, 1 male, dive/sample T421-A5, other data same as above; ZMUC-CRU- 9979, 1 female, 1 male, dive/sample T421-A5, other data same as above; 1 female, NHM 2007.82 and 1 male, NHM 2007.81, dive/sample T421-A5, other data same as above.

Diagnosis. All pereonites and pleonites 1–3 with a dorsal carina, carinae increasing in size and sharpness posteriorly; integument of body and coxae sculptured; head with a dorsal bulge; coxa 2, anterior margin concave, anterodistal corner narrowly rounded; pereopod 7, posterodistal margin of basis concave, with 3–5 robust setae at distal corner.

Description. HOLOTYPE, adult female, CMNC 2007-0002.

Pereon and Pleonites 1–3 ( Fig. 1 View FIGURE 1 ), all segments dorsally carinate, carinations becoming increasingly acute starting on pereonite 6; body surface sculptured, ridged, lateral margins of pereonites above coxa with a distinct bulge. Urosomite 1 ( Fig. 1 View FIGURE 1 ), dorsal tooth strong, acute, upright, upper margin weakly convex. Urosomites 2–3 ( Fig. 1 View FIGURE 1 ), dorsally smooth, 2 much shorter.

Head ( Fig. 1 View FIGURE 1 ), dorsal margin with a prominent distal hump or bulge; eye absent; rostrum very short, rounded; midcephalic margin of head straight; lateral cephalic lobe broadly triangular, apex acute, lower margin rounded. Antenna 1 ( Fig. 1 View FIGURE 1 ), length about one-half body, peduncular article 1 robust, with a small dorsomedial and proximolateral protuberance, article 3 quite short, articles 1–3 in ratio of 1: 0.41: 0.19; callynophore strong, length slightly less than peduncular article 1, densely furnished with aesthetascs medially; accessory flagellum 6-articulate; primary flagellum 28-articulate, calceoli absent. Antenna 2 ( Fig. 1 View FIGURE 1 ), slightly longer than antenna 1, peduncular article 5 slightly longer than 4, both articles with slender setae; flagellum about 32-articulate, calceoli absent.

Upper lip ( Fig. 2 View FIGURE 2 ), anterior surface finely setose, distal margin narrowly rounded. Lower lip ( Fig. 2 View FIGURE 2 ), outer lobes broad, robustly setose on inner distal margins, mandibular lobes elongated, narrow. Mandible ( Fig. 2 View FIGURE 2 ), incisors strongly toothed, 7-dentate; left lacinia mobilis 6-dentate, right lacinia robust, complex, with many irregularly sized teeth; accessory setal rows with 8–10 long, pectinate robust setae interspersed with fine plumose setae; molar large, narrow, triturative, with pits on surface, long plumose seta present; palp attached level with molar, article 1 short, length equal to width, posterodistally with a rounded lobe, article 2 length 3.61 x article 1, with 5D2-setae and 22A2-setae, article 3 ovate, length 0.72 x length of article 3 with 4A3- setae, 28D3-setae along posterodistal two-thirds of margin and 5E3-setae. Maxilla 1 ( Fig. 2 View FIGURE 2 ), inner plate tapering distally, inner margin fully lined with ~ 34 long, plumose setae, apical seta strongest; outer plate with 11 setal teeth (ST) in a 7/4 arrangement, ST1–2 large, stout with 1–2 cusps, ST3–4 large, slender, with 4 cusps, ST5–6 slender, finely-cusped, ST7 slender, finely-cusped and slightly displaced from ST6, inner row with STA large, stout, with 2 cusps, STB-D slender, multi-cusped; palp stout, 2-articulate, article 1 short, length 0.45 x article 2, with 1 slender distolateral seta, article 2 widening distally with 10 distal conical robust setae, 1 slender distolateral robust seta, and 7 submarginal distolateral slender setae. Maxilla 2 ( Fig. 2 View FIGURE 2 ), inner plate slightly shorter and narrowing distally, both plates distally setose, inner plate with strong mediofacial row of 32 long, plumose setae. Maxilliped ( Fig. 2 View FIGURE 2 ), basal article with ~ 9 very long setae on lateral margin, reaching half-way along palp article 1, inner plate subrectangular, reaching to distal end of palp article 1, distal margin setose with 3 strong nodular robust setae, medial margin lined with 15 long plumose setae; outer plate subovate, broad, reaching about 0.7 x length of palp article 2, medial margin lined with 13 stout robust setae and ~ 40 submarginal setae, distolaterally with strong setae; palp 4-articulate, article 2 longest, with strong medial setae, article 3 length 0.85 x article 2, with stout mediofacial, distomedial and lateral setae, dactylus short, length 0.53 x article 3, inner margin with a slender tooth and setules.

Gnathopod 1 ( Fig. 3 View FIGURE 3 ), coxa short, length 0.72 x length of coxa 2, partially covered by coxa 2, distal margin rounded, with relatively long setae; basis, length 3.33 x width, anterior and posterior margins strongly setose, lined with many long setae, strongest anteriorly; ischium, length 0.43 x basis, posterior margin setose; merus short, length 0.6 x ischium, posterodistal margin with 2–3 rows of strong setae and mat of short setules; carpus long, length 1.39 x propodus, posterior margin strongly setose, with many stiff pectinate setae; propodus subchelate, rectangular, length 2.1 x width, length 0.72 x carpus, medial and posterior margins with clusters of setae, palm transverse, convex, palmar corner defined by 3 medial and 2 lateral robust setae; dactylus stout, not quite reaching palm corner, anterior margin with a proximal seta, posterior margin with a slender tooth and 3 setules at base of the strong unguis. Gnathopod 2 ( Fig. 3 View FIGURE 3 ), coxa rectangular, long, length 2.23 x width, anterior margin concave, anterodistal corner narrowly rounded, distal margin lined with short setae; basis, length 3.66 x width, anterior and posterior margins lined with many long setae; ischium elongate, length 0.64 x basis; merus, length 0.63 x ischium, posterodistal margin with rows of strong setae; carpus long, length 1.39 x propodus, anterodistal margin with long setae, posterior margin strongly setose with 7 rows of submarginal setae, with many stiff pectinate setae; propodus subchelate, narrow-rectangular, length 2.53 x width, length 0.73 x carpus, medial and posterior margins with clusters of setae, palm transverse, convex, palmar corner defined by 4 medial and 3 lateral robust setae, lateral setae strongest and pectinate; dactylus stout, not quite reaching palm corner, anterior margin with a proximal seta, posterior margin with a slender tooth and 3 setules at base of the strong unguis.

Pereopod 3 ( Fig. 4 View FIGURE 4 ), coxa long, length 1.94 x width, distal margin convex, lined with short setae; basis curved, widening distally, both margins with clusters of setae; ischium short, length 0.83 x width, posterior and distal margin with setae; merus length 2.63 x width, very weakly produced anterodistally, both margins with setae, distally with long setae; carpus length 0.8 x merus, both margins with setae, distally with long setae; propodus length 1.43 x carpus, anterior margin with 4 fine setae, distally with 2 fine setae, posterior margin with 5 robust setae and fine setae, distally with 2 robust setae; dactylus length 0.48 x propodus, slightly curved. Pereopod 4 ( Fig. 4 View FIGURE 4 ), similar to pereopod 3 except; coxa 4, slightly shorter than coxa 3, distal margin more strongly convex, posterodistal lobe very weak, nearly lacking, posterior margin very weakly excavated; basis more weakly curved. Pereopod 5 ( Fig. 4 View FIGURE 4 ), coxa length 0.9 x width, anterolobate, anterior lobe narrow, subovate, posterior lobe broader, sculptured laterally above posterior lobe; basis very slightly expanded proximally, length 2 x width, posterior margin proximally with 4–5 serrations and setules, margin medially constricted with distal half narrower than proximal half, distal margin straight, lacking lobe at corner; ischium short, length 0.83 x width; merus, anterior and posterior margins with robust and slender setae, very weakly produced posterodistally; carpus length 1.16 x merus, both margins with robust setae, posterodistal corner with a longer robust seta; propodus length 1.11 x carpus, both margins with robust setae, posterodistal corner with long slender setae; dactylus length 0.41 x propodus, curved. Pereopod 6 ( Fig. 4 View FIGURE 4 ), longer than pereopod 5; coxa length 0.8 x width, anterior lobe narrowly rounded, posterior lobe broad, distally with setules; basis similar to above except posterior proximal margin very gently convex and with more serrations; ischium-dactylus similar to above. Pereopod 7 ( Fig. 4 View FIGURE 4 ), length subequal to pereopod 6; coxa length 0.77 x width, ovate; basis length 2.15 x width, expanded proximally, with ~ 12 serrations and setules, posterodistal margin concave, posterodistal corner with 3 strong robust and 2 slender setae; ischium-dactylus similar to Gills ( Figs. 3–4 View FIGURE 3 View FIGURE 4 ), on pereopods 2–7, largest on pereopods 2–4, ovate accessory appendage (lobe) positioned proximolaterally on gills 2–6, largest on gills 5–6. Brood Plates ( Figs. 3–4 View FIGURE 3 View FIGURE 4 ), on pereopods 2–5, long, narrow, length 5– 6.6 x width (longest on pereopod 2), curving distally, with 18–32 long slender setae (18 on pereopod 5 plate, 32 on gnathopod 2 plate). Pleopods ( Fig. 4 View FIGURE 4 ), strong, peduncle of pleopod 1 shortest, peduncles with 2 mediodistal coupling hooks; inner ramus with ~ 5–7 proximal, slender distally bifid setae. Epimeron 1 ( Figs. 1 View FIGURE 1 , 4 View FIGURE 4 ), distal margin truncate, with 8 setae, posterior margin convex. Epimeron 2 ( Figs. 1 View FIGURE 1 , 4 View FIGURE 4 ), distal margin with 7 setae, posterior margin convex proximally, straight distally, posterodistal corner with a small tooth. Epimeron 3 ( Figs. 1 View FIGURE 1 , 4 View FIGURE 4 ), posterior margin slightly convex, distal margin with 11 setae, posterodistal corner with a strong, acute tooth and setule.

Uropod 1 ( Fig. 5 View FIGURE 5 ), peduncle length 0.95 x length of outer ramus, with 7 dorsolateral and 1 large robust seta distolaterally, dorsomedially with 5 slender robust setae, ventrolaterally with 7 setae; rami strongly lanceolate, edges finely serrate, subequal, outer with 6 lateral and 7 medial robust setae; inner ramus with 5 lateral and 13 medial robust setae. Uropod 2 ( Fig. 5 View FIGURE 5 ), peduncle 0.83 x length of outer ramus, with 3 dorsolateral and 2 dorsomedial robust setae; rami as above except, outer ramus short, 0.76 x inner, with 4 lateral robust setae, medial margin with 5 robust setae proximally; inner ramus with 7 lateral robust setae and 9 medial robust setae. Uropod 3 ( Fig. 5 View FIGURE 5 ), peduncle about 0.67 x outer ramus, with 4 distomedial, 3 apicodorsal, and 3 lateral robust setae; outer ramus 1.2 x inner, two-articulate, article 1 with 2 lateral and 1 distal robust seta, medial margin with 3 robust setae and 1 distal robust seta, article 2 long, length 0.5 x article 1; inner ramus with 3 lateral and 6 medial robust setae, with 5 plumose setae. Telson ( Fig. 5 View FIGURE 5 ), length 1.5 x width, dorsolateral margins each with 3 robust setae, lobes tapering distally, armed with 1 strong and 2 weak robust setae at tip, cleft 80 %.

Etymology. The species name refers to the concave shape of both the anterior margin of coxa 2 and the posterodistal corner of the basis of pereopod 7.

Condition. All appendages present.

Variation. Valettiopsis concava exhibits some sexual dimorphism and allometric variability. In general, mature males have longer antennae, (especially antenna 2), gnathopods, pereopods and uropods, but proportions are similar to the females. Mature male specimens possess a larger callynophore on antennae 1 (longer than antenna 1 peduncular articles 1–3) and have a longer accessory flagellum with more articles (8 vs 6). Peduncular articles 4–5 of antenna 2 are slightly thickened and fully lined medially with brush setae and like the female, lack calceoli. The rami of uropod 3 are more powerful in the male and the inner ramus of uropod 3 is proportionately longer in mature males and fully lined medially with long, plumose setae. In the outer ramus of uropod 3, the length of article 2 relative to article 1 is only 0.33, compared to 0.5 in the female ( Fig. 5 View FIGURE 5 ). The uropod 3 in small, immature males is similar to females. There are more robust setae on uropods 1–2 of male specimens. For example, the allotype male uropod 1 has a total of 22 (vs. 12) robust setae on the peduncle and the inner ramus has 31 (vs. 18) robust setae.

The dorsal carinations of the anterior pereonites of small specimens are more prominent and rounded than in larger specimens, which become flattened ( Fig. 1 View FIGURE 1 ).

In the mouthparts, asymmetry is present in the palp of maxilla 1 in both sexes. The right palp is much wider distally and has conical shaped, robust setae distally. The left palp is much narrower and has slender robust setae distally ( Fig. 2 View FIGURE 2 ).

This species exhibits dimorphism in the shape of the urosomite 1 tooth. The tooth of mature male specimens has a strongly convex dorsal margin and it is directed backward ( Fig. 1 View FIGURE 1 ); in small specimens of both sexes and mature females the tooth margin is gently convex and more upright ( Fig. 1 View FIGURE 1 ). Prior to using this character for a Valettiopsis species, it is important to check both sexes and all sizes, to determine its variability. Urosomite 1 tooth shape has been used previously as a diagnostic species character (see Horton 2004) for V. minuta , but the variation, if present, was not indicated.

Remarks. Valettiopsis concava is easily differentiated from the six smooth-bodied species in the genus in possessing a single dorsal carina on all pereonites and pleonites and in having a ridged and sculptured integument. The only other carinate species, V. multidentata J.L. Barnard, 1961 described from the Tasman Sea, has carinations commencing on pereonite 5 and lacks the sculptured cuticle. Examination of the type specimen of V. multidentata (ZMUC, CRU 7426, Sta. 665, Kermadec Trench) has clearly revealed that V. concava is distinct. The new species also differs from V. multidentata by possessing a concave anterior margin of coxa 2 (vs. convex), the narrower propodus of gnathopod 2 which is 0.73 x length of the carpus (vs. broader propodus which is 0.9 x carpus), narrower anterior lobe of coxa 5 (vs. broad) and a concave posterodistal margin of the Distribution. North-east Pacific, off Point Conception and Monterey Bay, California in 3607–4100 m depth. Attracted to baited traps and found on glass sponge stalks.

Serejo & Wakabara (2003) and Horton (2004) have provided keys to species of Valettiopsis . A key is here presented to include the new species.