Spongiopsyllus athosi Farias, Santana, Neves & Johnsson, 2024, sp. nov.

Spongiopsyllus athosi sp. nov. urn:lsid:zoobank.org:act: BAE1A489-E87E-472E-9F14-3FA99AA596C7 Figs 1–2, Tables 1, 4 Diagnosis Body shield-form dorso-ventrally flattened, pedigerous somite three and four not fused. Antennule 16-segmented, presenting fusions of segments (III–VI, IX–XIII, XXIII–XXVIII), and with aesthetasc on segment 14. Antenna with 4 spinules on outer, and 1 spinule on inner margins of exopod segment, and endopod 2-segmented with 2 long and 2 short apical setae. Maxillule with 3 setae on inner lobe, and 4 setae on outer lobe. Maxilliped with endopod 3-segmented, showing 2 setae on first segment, 1 on second and three on third; setal formula (2,1,1+claw). Etymology The tapered morphology of leg 1 third endopodal segments, showing sharpened processes, inspired the species name referring to the swordsman ‘Athos’, one of Alexandre Dumas’ characters from ‘ The Three Musketeers ’, a historical adventure novel written in 1844. Material examined Holotype BRAZIL • ♀; Bahia, Todos-os-Santos Bay, Pedra Cardinal; 12°50′15″ S, 38°32′58″ W; 20 May 2017; L.C.C. Silvany leg.; manually collected, associated with the sponge Aplysina cauliformis (Carter, 1882); UFBA 3291. Description Female Body length (from cephalosome to the furcal rami) 1170 µm and greatest body width (cephalosome) 850 µm. Prosomal shield flattened (Fig. 1A), with radiating bands along outer margin. Pedigerous somites 2–4 free. Urosome (Fig. 1B) 4-segmented. Genital double-somite fused with fifth pedigerous somite, 150 µm long, and with length:width ratio 1.3:1. Three postgenital somites present, all wider than long, 80 ×67, 75 ×47, 65 ×32 µm, respectively. Prosome:urosome length ratio 1.5:1. Caudal rami elongate, 107 µm long, with setules along medial-distal inner margin, and armed with 6 setae distally. Antennule (Fig. 1C) slender, 251 µm long (not including setae), and 16-segmented. Length of segments: 62, 22, 24, 10, 9, 13, 7, 10, 10, 12, 11, 11, 12, 14, 8 and 16 µm, respectively. Segmental homologies and setation as follows: I-1; II-2; III–VI-7; VII-2; VIII-2; IX–XIII-6; XIV-2; XV-2; XVI-2; XVII-1; XVIII-2; XIX-2; XX-2; XXI-1+ae; XXII-2; XXIII–XXVIII-8. All setae naked. Aesthetasc 102 µm long. Antenna (Fig. 1D) 224 µm long (including distal claw); coxa 24 µm long; basis 76 µm long. Exopod 1-segmented, 65 µm long, with 2 long slender distal setae, and 5 small spinules along margins. Endopod 2-segmented; first segment 53 µm long, unarmed, with 7 spinules on outer margin; second segment 22 µm long, ornamented with row of setules along outer margin, and armed with 2 long and 2 short naked setae; distally curved claw (49 µm) with bump-like projection subdistally. Oral cone 210 µm long, reaching first postgenital somite (Fig. 1A). Mandible comprising stylet and slender 2-segmented palp (Fig. 1E) measuring 40 and 62 µm long, respectively. Palp with second segment armed with 2 apical, plumose setae and ornamented with setules along outer margin. Stylet slender and pointed, 142 µm long. Maxillule (Fig. 1F) bilobed; inner lobe 68 µm long, armed with 3 long apical setae. Outer lobe 49 µm long, armed with 4 short setae and ornamented with setules along outer margin; all setae naked. Maxilla (Fig. 1G) with syncoxa and curved claw measuring 217 and 134 µm long, respectively; claw with soft bump-like projection subdistally. Maxilliped (Fig. 2A) 5-segmented, 298 µm long (excluding claw); syncoxa 84 µm long, with inner seta and 3 setules on distal inner margin; basis 138 µm long, unarmed. Endopod 3-segmented, 22, 23, and 31 µm long, respectively; first segment with 2 naked unequal setae; second segment with distal small seta; third segment with small distal seta and curved claw measuring 56 µm long. P1–P3 (Fig. 2B–D) biramous, with 3-segmented rami. P4 (Fig. 2E) with 3-segmented exopod and endopod absent. Armature formula reported in Table 1. First and second exopodal segments of P1 (Fig. 2B) with setules on outer margins; second segment with setules on inner margin; outer margin of third segment with spinules, inner margin naked. Second endopodal segment of P1 (Fig. 2B) with setules on outer margin and moderate sharpened process on distal margin. Third endopodal segment of P1 (Fig. 2B) prolonged distally into sharpened process, therefore distal setae located sub-distally on inner margin. First and second exopodal segments of P2 (Fig. 2C) with outer margins naked, second exopodal segment of P2 with few setules on medial inner margin. Second endopodal segment of P2 (Fig. 2C) with spinules on outer margin and setules on inner margin; third endopodal segment with setules on proximal inner margin. Basis of P2 and P3 with spinules on inner and outer margins, respectively. P3 exopodal outer margins with spinules (Fig. 2D); first and second endopodal segments with setules on both margins; second endopodal segments with one small and one tiny sharpened process on distal margin; third endopodal segment with small sharpened process on distal margin. P4 exopodal outer margin with spinules (Fig. 2E,), which are larger on second segment than on other segments; medial distal margins of first and second segments with two tiny, sharpened processes on medial distal margin. Free exopodal segment of P5 (Fig. 1B) elongate, curved, 207 µm long, longer than genital double-somite, and armed with 2 distal and one outer medial plumose seta. Male Unknown.