Photis guerrai, Tato & Moreira, 2017

Tato, Ramiro & Moreira, Juan, 2017, Two new species of the Suborder Senticaudata (Crustacea: Amphipoda) from the upper continental slope off Galicia (NW Iberian Peninsula), Zootaxa 4300 (2), pp. 217-237 : 228-229

Photis guerrai sp. nov.

( Figs 7–11 )

Material examined. Holotype: AdUlt male, 4.3 mm, ethanol in the mUseUm (MHNUSC 10068); “Diva Artabria I” crUise; sample DRN-03-1000, 2003/09/16; 43° 53.575’ N; 008° 56.868’ W; 1005 m depth; rocky bottoms). Paratypes: 2 adUlt males, 3–3.6 mm long (MHNUSC 10069); “Diva Artabria I” crUise; sample AT-03-800, 2003/ 09/15; 43° 51.774’ N; 008° 53.640’ W; 800 m depth; rocky bottoms); 5 adUlt males and 1 adUlt female, 2.1–3.3 mm (MHNUSC 10070); “Diva Artabria I” crUise; sample EBS-03-800, 2003/09/15; 43° 51.873’ N; 008° 53.683’ W); 1 adUlt male of 3.5 mm (MHNUSC 10071 “A Selva 08” crUise; sample 15-EBS-2008, 2008/09/25; 43° 19.920’ N; 009° 38.130’ W; 1267 m depth; coarse sand bottoms).

Diagnosis. Head withoUt eyes, with pointed cephalic lobes. Antennae with ventral setae, sUbeqUal in length, both close to total body length. Coxal plates well developed. Basis of gnathopod 2 with a distal lobe overlapping ischiUm. Pereopods 5–6 with accessory spine on dactylUs. Epimeral plates with roUnded posterodistal corner. Inner ramUs of Uropod 3 very redUced; oUter ramUs elongate with distal setae. Telson slightly roUnded with setae inserted in apical notch.

Description of holotype. Head ( Fig. 7 ) slightly dorsoventrally compressed; with pointed cephalic lobes, eyes absent.

Antenna 1 ( Fig.7 B). AboUt as long as body length. PedUncle article 1 aboUt twice as long as broad, with distal ventral setae; article 2 elongate and narrow with 6 groUps of ventral setae; article 3 elongate and narrow, slightly shorter than article 2, with 5 groUps of ventral setae. FlagellUm with 6 articles, each with ventral setae. No accessory flagellUm.

Antenna 2 ( Fig. 7 C). Similar in length to antenna 1. PedUncle article 2 short and broad; article 3 two times longer than broad, withoUt setae; articles 4–5 elongate and narrow with ventral long setae. FlagellUm with 6 narrow articles, each with distal ventral setae.

Mouthparts. Mandible ( Fig. 8 A) molar roUnded and well developed, with 5 short stoUt setae and a row of small setae close to the apex ( Fig. 8 D); incisor well developed; setal row with 6 composite setae ( Fig. 8 B), last 2 stoUt setae near lacinia mobilis redUced in length; mandibUlar palp with 3 articles; article 1 short, withoUt setae; article 2 elongate with long setae; article 3, with mediofacial setae along distal half and long distal pappose setae ( Fig. 8 C). Maxilla 1 inner plate redUced, with 1 apical seta; oUter plate with 8 bifid stoUt setae on distal margin ( Fig. 8 E, F); palp 2-articUlate, with 4 sUbdistal and 2 distal stoUt setae ( Fig. 8 E). Maxilla 2 ( Fig. 8 G); oUter plate bigger than inner plate, both with long plUmose setae ( Fig. 8 H). Maxilliped ( Fig. 8 I) inner plate with 3 distal stoUt setae and 6 plUmose setae on distal margin ( Fig. 8 J); oUter plate reaching more than 1/3 of palp article 2; with 5 stoUt setae and 3 cUspidate setae on sUbdistal/distal margin ( Fig. 8 K); with simple setae along anterior face; palp with 4 articles; article 1 short; article 2 elongate, with nUmeroUs setae on inner margin; article 3 aboUt half length of article 2, with long plUmose and simple setae; article 4 cUrved with 1 dorsal setae and 1 short distal seta.

Coxal plates ( Fig. 7 A). Well developed, sUbqUadrate.

Gnathopod 1 ( Fig. 9 A). Typical of genUs. Basis elongate with short distal setae on posterior margin and 1 long median seta on anterior margin. IschiUm short and broad with posterior distal setae. MerUs short and broad, distal posterior margin densely covered with setae distally. CarpUs inserted on merUs anterior margin, wider distally, with 2 rows of variable sized setae on posterior margin and 1 distal stoUt seta and nUmeroUs simple setae on anterior margin. PropodUs oval, palm convex with small notch and 3 stoUt setae near articUlation with dactylUs, posterior margin with 3 transverse rows of simple and plUmose setae; anterior margin with 2 transverse rows of setae and 2 long distal setae. DactylUs well developed, cUrved, with setae on anterior margin and short setae associated with serrations along posterior margin; nail present ( Fig. 9 B).

Gnathopod 2 ( Fig. 9 C). Basis elongate, wider distally, with distal lobe overlapping ischiUm and short setae along anterior margin. IschiUm short and broad with 2 short distal posterior setae. MerUs similar to gnathopod 1 merUs, with distal row of setae on posterior margin. CarpUs triangUlar and inserted on merUs anterior margin, with distal tUft of setae on posterior margin and with 3 short sUbdistal setae on anterior margin. PropodUs well developed; palmar margin concave with short and long setae; posterior margin with 3 transverse rows of setae and 3 stoUt setae, anterior margin with sUbdistal and distal setae. DactylUs well developed, cUrved, with 1 proximal setae on anterior margin, with short setae associated with 2 denticles and minUte serrations on posterior margin ( Fig. 9 D); withoUt visible nail.

Pereopod 3 ( Fig. 10 A). Basis elongate, with 1 short seta on posterior margin and longer sUbdistal setae on anterior margin. IschiUm short and broad with posterodistal setae. MerUs 3 times longer than broad, with long setae on anterior margin. CarpUs redUced, 2 times longer than broad, with distal setae on anterior and posterior margins. PropodUs elongate and narrow, with setae along anterior margin. DactylUs simple, well developed and slightly cUrved; withoUt nail.

Pereopod 4 ( Fig. 10 B). Similar to pereopod 3 in shape and setae density. Basis elongate with 2 long posterior setae. IschiUm short and broad with distal setae on posterior margin. MerUs elongate with short distal setae on both anterior and posterior margins and 1 short proximal seta on posterior margin. CarpUs redUced, similar to pereopod 3 carpUs, with distal setae. PropodUs elongate and narrow, slightly cUrved with proximal and 1 distal setae on anterior margin. DactylUs aboUt 2/3 of propodUs length, slightly cUrved and naked withoUt nail.

Pereopod 5 ( Fig. 10 C). Basis 2 times longer than broad, with setae on posterior margin. IschiUm short and broad, with short sUbdistal setae on anterior margin. MerUs elongate, 2 times longer than broad, with distal setae on dorsal and ventral margins. CarpUs similar in length to merUs, with 1 long seta and distal setae on distal margin. PropodUs elongate and narrow with 2 simple setae and 2 stoUt setae on distal margin. DactylUs redUced and cUrved, with 1 accessory stoUt setae and 1 short seta ( Fig. 10 D).

Pereopod 6 ( Fig. 11 A). Basis oval, longer than broad, with short setae on anterior and posterior margins. IschiUm short and broad, with 1 distal seta. MerUs and carpUs similar in shape to those of pereopod 5 with distal setae. PropodUs elongate and narrow, with 2 stoUt setae and a distal row of setae aroUnd dactylUs insertion. DactylUs very redUced, cUrved and naked, with small accessory stoUt setae and withoUt nail.

Pereopod 7 ( Fig. 11 B). Longer than pereopods 5–6. Basis oval, with setae on anterior and posterior margins. IschiUm short and broad with distal seta on anterior margin. MerUs elongated, 3 times longer than broad with 1 long distal seta and 3 short setae along posterior margin, with 1 distal seta on anterior margin. CarpUs elongated, almost 3 times longer than broad, with long and short setae on distal margin and 1 short seta on posterior margin. PropodUs elongate and narrow, slender than carpUs, with 2 short mediofacial stoUt setae and a row of distal long setae aroUnd insertion of dactylUs. DactylUs simple, cUrved and elongate, with nail.

Epimeral plates. RoUnded, withoUt setae or processes.

Uropod 1 ( Fig. 11 C). PedUncle elongate, 3 times longer than broad, with 3 small stoUt setae along dorsal margin and 2 distal stoUt setae; rami shorter than pedUncle, oUter ramUs with 2 dorsal stoUt setae; inner ramUs naked, slightly longer than oUter.

Uropod 2 ( Fig. 11 D). Shorter than Uropod 1. PedUncle elongate with 2 distal stoUt setae; oUter ramUs shorter than pedUncle, with dorsal median stoUt setae; inner ramUs longer than oUter, with a dorsal medial spine.

Uropod 3 ( Fig. 11 E). RedUced. PedUncle short, narrow on distal margin; oUter ramUs longer than pedUncle, with a small distal article bearing 2 long distal setae; inner ramUs very redUced, conical, withoUt setae or stoUt setae.

Telson ( Fig. 11 G). TriangUlar, with 2 sUbdistal notchs of short simple setae.

Sexual dimorphism. Males and females of P. guerrai sp. nov. are very mUch alike as it happens in other species of the genUs ( Myers 2009). Sexes can only be distingUished in most of cases by the presence of secondary sexUal strUctUres (oostegites) or less developed gnathopods in females.

Type locality. Ferrol Canyon, Galician continental margin (NW Iberian PeninsUla). 43° 53.575’ N; 008° 56.868’ W, 1005 m depth.

Distribution and habitat. Hard bottoms between 800 and 1267 m depth in the Ferrol Canyon (off Galician coast, NW Iberian PeninsUla).

Etymology. This species if named after oUr friend José ManUel GUerra García (Universidad de Sevilla, Spain) for his friendship and many contribUtions to the knowledge of amphipods, particUlarly aroUnd the Iberian PeninsUla.

Remarks. Photis guerrai is a blind species as 4 of the 69 known Photis species ( P. kurilica GUrjanova, 1955 ; P. caeca Barnard, 1962 ; P. malinalco Barnard, 1967 ; P. typhlops Conlan, 1994 ). However, it can be easily distingUished fom these foUr blind species by the presence of an anteriodistal lobe on the basis of gnathopod 2. Other morphological characters can also be Used. Photis kurilica differs in having qUandrangUlar cephalic lobes, higher density of simple long setae on gnathopods and stoUt setae on Uropods. Photis caeca also shows qUandrangUlar cephalic lobes. Photis typhlops bears more developed coxal plates with more obliqUe distal margin on coxae 1-2. Photis malinalco differs by the relative length of inner and oUter rami of Uropod 3.

Figures

FIGURE 7. Photis guerrai sp. nov., Holotype, MHNUSC 10068. A, habitus, lateral view; B, antenna 1; C, antenna 2. Scales: 0.5 mm.

FIGURE 8. Photis guerrai sp. nov., Holotype, MHNUSC 10068. A, mandible; B, mandible, composite setae on molar process; C, mandible, pappose seta on palp article 3; D, mandible, ornamentation of molar process; E, maxilla 1; F, maxilla 1, distal stout setae on outer plate; G, maxilla 2; H, maxilla 2, distal setae on outer plate; I, maxilliped; J, maxilliped, distal setae on inner plate; K, maxilliped, distal setae on outer plate. Scales: 0.1 mm.

FIGURE 9. Photis guerrai sp. nov., Holotype, MHNUSC 10068. A, gnathopod 1; B, gnathopod 1, ornamentation of dactylus; C, gnathopod 2; D, gnathopod 2, ornamentation of dactylus. Scales: 0.1 mm.

FIGURE 10. Photis guerrai sp. nov., Holotype, MHNUSC 10068. A, pereopod 3; B, pereopod 4; C, pereopod 5; D, pereopod 5, accessory stout seta on dactylus. Scales: 0.1 mm.

FIGURE 11. Photis guerrai sp. nov., Holotype, MHNUSC 10068. A, pereopod 6; B, pereopod 6, accessory stout seta on dactylus; C, pereopod 7; D, uropod 1; E, uropod 2; F, uropod 3 and telson; G, telson (dorsal view). Scales: 0.1 mm.