Photis butalus Sir & White, 2025, sp. nov.
Creators: name: Sir, Sally J.
name: White, Kristine N.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Photidae
Photis
Photis butalus

description: Photis butalus sp. nov.
Figs 15, 16, 17, 32E
Type locality.
Bocas del Toro, Panama: Swan Cay; 9.4533°N, 82.2983°W, depth 3 m, among brown algae, hydroids, and filamentous algae.
Material examined.
Holotype: Panama • 1 ♂, 2.1 mm; Bocas del Toro, Swan Cay; 9.4533°N, 82.2983°W; depth 3 m, among brown algae, hydroids, and filamentous algae; 4 Aug 2005; T. A. Haney leg.; USNM 1743981. Paratype: Panama • 1 ♀, 2.3 mm; same station data as for preceding; GCRL 6669. Other material: Panama • 1 ♂, 1.8 mm; 4 ♀, 2–2.6 mm; 1 juvenile, mm; same station data as for preceding; GCRL 6670.
Diagnosis.
Eye well developed, not touching outer margin of ocular lobe. Gnathopod 1 propodus palm entire. Pereopod 6 of adult male greatly enlarged; merus ovate; propodus thick, width 0.4 × length, palmar margin minutely serrate with short setae, one short subtriangular seta present; dactylus apical margin subacute. Pereopod 7 dactylus with posterior and anterior accessory claws.
Description.
Male (holotype, 2.1 mm). Head. Eye well developed, not touching outer margin of ocular lobe. Antenna 2 flagellum 5 - articulate. Maxilliped inner plate lined with setae along inner margin, two rows of apical setae present, outer plate with row of four thick setae, and six sagittate-shaped setae. Lower lip inner lobes rounded, outer lobes with large gape, apically setose, with few thick bifurcate setae; inner plate length 0.8 × length of outer plate, apically setose. Maxilla 1 inner plate small, bare; outer plate with two rows of five apical bifurcated robust setae; palp bi-articulate, article 2 lined with marginal setules, apical margin with three bifurcated robust setae. Maxilla 2 inner lobe with two rows of marginal setae; outer lobe with two rows of apical setae. Mandibles similar, molar small; palp tri-articulate, article 3 lined with fine setules.
Pereon. Coxae sparsely setose. Coxa 1–4 subrectangular, longer than wide. Gnathopod 1 subchelate; basis anterior and posterior margins with few long setae; merus with posterodistal cluster of setae; carpus subequal in length to propodus, densely setose; propodus palm convex, serrate, proximal margin with one large robust seta; dactylus lined with minute stout setae, with one serration at distal end. Gnathopod 2 subchelate; basis anterior and posterior margins each with one long seta and one short distal seta; merus with posterodistal bunch of long setae, posterodistal margin with fine setules; carpus subtriangular, with posterodistal cluster of fine setae; propodus palm with weak excavation, palmar robust seta present; dactylus extending past excavation of propodus palm, lined with minute stout setae, with one distal serration. Pereopods 3 and 4 bases thick, posterodistal margin with few long setae; dactylus apically subacute. Pereopod 3 merus anterodistal margin densely setose. Pereopod 5 basis nearly circular, sparsely setose; propodus with two posterodistal robust setae; dactylus stout with accessory claw. Pereopod 6 of adult male greatly enlarged; merus ovate; propodus thick, width 0.4 × length, palmar margin minutely serrate with short setae, one short subtriangular robust seta present; dactylus apical margin subacute. Pereopod 7 basis narrowing distally; remaining articles slender; propodus distal margin sparsely lined with short setae and one short subtriangular robust seta; dactylus with posterior and anterior accessory claws.
Pleon. Uropod 1 peduncle 1.3 × length of inner ramus, with three marginal robust setae and lined with fine setules; inner ramus 1.1 × length of outer ramus, with one marginal stout seta, lined with marginal setules, apex with two robust setae; lined with marginal setules, apex with three robust setae. Uropod 2 peduncle with two distal robust setae, subequal in length with inner ramus; inner ramus 1.2 × length of outer ramus, one marginal robust setae, inner margin lined with setules, apex with two robust setae; outer ramus outer margin lined with setules, with one marginal robust setae, apex with two robust setae. Uropod 3 peduncle 3.9 × length of inner ramus, with two distal setae; inner ramus 0.4–0.5 × length of outer ramus, bare; outer ramus bi-articulate, first article outer margin lined with setules, with three long distal setae; second article with one distal seta. Telson narrowing distally, apically rounded with four dorsal setae.
Female (paratype, 2.3 mm). Similar in all aspects to the male with the exception of the following: pereopod 6 merus not enlarged, propodus width 0.2 × length, smooth; dactylus apically acute with accessory claws.
Etymology.
After the Latin bu, meaning large and talus, meaning ankle, heel, die and referring to the greatly enlarged pereopod 6, specifically the thickened propodus, of males of this species.
Distribution.
Panama: Bocas del Toro (present study).
Ecology and remarks.
This species occurs among brown algae, hydroids, and filamentous algae at a depth of three meters.
Photis butalus sp. nov. is similar to Photis trapherus Thomas & Barnard, 1991 and Photis elephantis Barnard, 1962 based on the enlarged male pereopod 6. The new species differs from P. trapherus in the following characters: eye not touching outer margin of ocular lobe (vs touching); entire gnathopod 1 propodus palm (vs slightly excavate); male pereopod 6 merus ovate (vs subrectangular), and propodus thick, posterior margin serrate (vs thin, smooth). The new species differs from P. elephantis in the following characters: ocular lobe pronounced, rounded (vs small, subquadrate); male pereopod 6 basis posteriorly rounded (vs posterior margin with acute distal point), merus posteriorly rounded (vs posterodistal margin produced into lobe), and propodus posterior margin serrate (vs smooth). This species is also similar to Photis sp. E LeCroy, 2000 but differs in the following characters: eye well developed (vs poorly developed); male pereopod 6 greatly enlarged (vs slightly enlarged), merus ovate (vs subrectangular with large posterodistal projection). This species is easily distinguishable from all remaining described Photis species based on the enlarged male pereopod 6. Ethanol-preserved specimens retained brown specks of color.
description: Published as part of Sir, Sally J. & White, Kristine N., 2025, Caribbean Amphipoda (Crustacea) of Panama. Part IV: parvorder Caprellidira, pp. 151-205 in ZooKeys 1234 on pages 151-205, DOI: 10.3897/zookeys.1234.145826