Apolochus dragensis, Dugger & White, 2025

Dugger, Abigail R. & White, Kristine N., 2025, Caribbean Amphipoda (Crustacea) of Panama. Part V: parvorder Amphilochidira, ZooKeys 1259, pp. 57-102 : 57-102

Apolochus dragensis sp. nov.

Figs 1 , 3 , 22 A

? Apolochus sp. A : LeCroy 2002: 231, fig. 237.

? Amphilochus neapolitanus : McKinney 1978: 137.

? Amphilochus neapolitanus : Thomas 1993: 24, fig. 25.

Type locality.

Bocas del Toro, Panama: Drago; 9.4181°N, 82.3375°W; depth 2–3 m; among coral rubble.

Distribution.

Panama: Bocas del Toro (present study).

Material examined.

Holotype: Panama • 1 ♀, 2.3 mm; Bocas del Toro, Drago ; 9.4181°N, 82.3375°W; depth 2–3 m; among coral rubble; 9 Aug 2021; K. N. White leg.; USNM 1762913 . Paratype: Panama • 1 ♀, 2.4 mm; Bocas del Toro, Swan Caye ; 9.4536°N, 82.3000°W; depth 2 m; among coral rubble; 24 June 2023; K. N. White leg.; USNM 1762914 .

Diagnosis.

Head anteroventral margin evenly rounded. Antenna 1 reaching the end of antenna 2 peduncle, with minute uni-articulate accessory flagellum. Mandibular molar reduced with a single apical spine. Gnathopod 2 carpal lobe nearly reaching palmar angle, propodus lacking anterolateral spines and anterodistal projection, anterodistal corner rounded, palm finely crenulate.

Description.

Female ( holotype, 2.3 mm). Head. Eye medium, oval, darkly pigmented in the center. Head anteroventral margin evenly rounded; rostrum reaching end of antennae 1 peduncle article 1. Antenna 1 shorter than antenna 2, nearly reaching end of antenna 2 peduncle; flagellum 5 - articulate; accessory flagellum uni-articulate, minute. Antenna 2 1.3 × length of antenna 1; flagellum 6 - articulate. Maxilliped inner plate lined with marginal setae; outer plate broad, margins lined with setae, apical margin with one bifurcate spine-seta, inner margin slightly concave; palp article 3 inner distal margin tuberculate. Maxilla 1 inner plate with 5 marginal spine-setae, palp segment 2 elongate with 5 distal setae. Maxilla 2 plates medium width, both plates lined with thin and medium width setae apically. Mandibular molar reduced, with single apical spine; left mandible with row of nine spine setae; palp missing. Upper and lower lips damaged in dissection.

Pereon. Coxae 1 short, ventral margin serrate; coxa 2 rounded, posteroventral margin serrate; coxa 3 anteriorly rounded, posteroventral margin serrate; coxa 4 rounded, posterior margin concave. Gnathopod 1 basis with one posteroventral seta; ischium as wide as long; carpal lobe reaching 0.67 × propodus posterior margin, distal margin with three setae; propodus palm convex, crenulate, with five setae in distal half; dactylus distal inner margin lined with setae. Gnathopod 2, basis bare; carpal lobe reaching palmar angle; propodus lacking anterolateral setae, anterodistal corner rounded, palm convex, crenulate, lined with small setae; dactylus slender, proximal margin lined with setae. Pereopods 3 and 4 dactyli medium, slender. Pereopods 5–7 bases rounded, pereopod 7 basis widest; dactylus medium, slender.

Pleon. Epimera 1–3 rounded, bare. Pleopods, rami longer than peduncle; pleopods 1–3 rami with eight, seven, and six articles, respectively. Uropod 1 slender, peduncle with four marginal spine-setae, 1.6 × length of rami; rami subequal, distal margins lined with setae; inner ramus lacking spine-setae; outer ramus with one spine-seta. Uropod 2 0.5 × length of uropod 1; peduncle with one distal spine-seta, 0.5 × length of inner ramus; inner ramus 1.7 × length of outer ramus, with one distal spine-seta; outer ramus with one distal spine-seta. Uropod 3 missing. Telson subtriangular, length 2.4 × width, apex narrowly rounded.

Variation ( paratype female, 2.4 mm). Mandibular spine row with eleven spine setae.

Male unknown.

Etymology.

After the place Drago, Bocas del Toro, Panama, meaning “ mouth of the dragon ” and referring to the type locality.

Ecology and remarks.

This species occurs among coral rubble at 2–3 m depth in Panama. This species is most likely the species called Amphilochus neapolitanus (Della Vale, 1893) from the western Atlantic and Caribbean Sea ( McKinney 1978; Thomas 1993) and Apolochus sp. A ( LeCroy 2002) based on the small, non-triturative molar and lack of anterolateral spines on the gnathopod 2 propodus. Apolochus dragensis sp. nov. can be differentiated from Apolochus neapolitanus based on the drawings from the Mediterranean illustrating a slightly triturative molar with two spines, a more densely setose uropod 2, and a wider telson ( Krapp-Schickel 1982). The reduced molar and lack of anterolateral spines on the gnathopod 2 propodus easily distinguish this species from all other species documented from the region who have a triturative molar and anterolateral spines on the gnathopod 2 propodus ( A. pillaii ( Barnard & Thomas, 1983) , A. cassahoya ( McKinney, 1978) , and A. delacaya ( McKinney, 1978)) . The new species shares a minute accessory flagellum on antenna 1 with A. pillaii , but A. cassahoya and A. delacaya have an accessory flagellum equal to the length of antenna 1 peduncle article 3. The new species shares a reduced molar with several other species but differs in the following ways: A. barnardi and A. staudei Hoover & Bousfield, 2001 have short, stout dactyls on pereopods 3 and 4 (vs medium length and slender); A. borealis ( Enequist, 1949) has a short carpus on gnathopod 2 (vs reaching the palmar angle); and A. litoralis ( Stout, 1912) has densely spinose uropods (vs few spine-setae). The new species is also easily distinguished from the other Apolochus species diagnosed here in having a round head margin (vs acute in A. cf. picadurus ( Barnard, 1962) and subquadrate in A. pillaii ). Apolochus dragensis sp. nov. differs from all other described Apolochus species in having a reduced molar. Living specimens are translucent with tan coloration on anterior and posterior ends, white opaque coloration on anterior half, rust coloration on pereopods 6 and 7, red stripes on antennae, and red eyes.

Figures

Figure 1. Apolochus dragensis sp. nov., female holotype, 2.3 mm, head, habitus, telson, uropod 1, and uropod 2. Scale bars: 0.5 mm.

Figure 3. Apolochus dragensis sp. nov., female holotype, 2.3 mm, pereopod 3, pereopod 4, pereopod 5, pereopod 6, pereopod 7, and pleopods 1–3. Scale bars: 0.5 mm.

Figure 22. Photographs of living specimens unless noted. A. Apolochus dragensis sp. nov.; B. Apolochus pillaii; C. Apolochus cf. picadurus (ethanol-preserved specimen); D. Seba cf. tropica (ethanol-preserved specimen); E. Stenothoe gallensis; F. Stenothoe minuta; G. Stenothoe valida (ethanol-preserved specimen). Scale bars: 1.0 mm.