Scottocheres spinoparva, Canário & Farias & Neves & Johnsson, 2022

Canário, Roberta, Farias, Amilcar, Neves, Elizabeth & Johnsson, Rodrigo, 2022, Description of a new Scottocheres Giesbrecht, 1897 (Copepoda, Siphonostomatoida Asterocheridae), including an emended diagnosis and key for the genus, Zootaxa 5222 (3), pp. 277-284 : 278-282

Scottocheres spinoparva sp. nov.

( Figs. 1–2 )

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Material examined. Holotype female ( UFBA 3266 ) and three paratypes ( UFBA 3267 , UFBA 3268 , UFBA 3269 ), collected from Porto da Barra Beach , Salvador, Brazil (13 o 0’135’’S, 38 o 32’189’’W) on March 11 th, 2016. All specimens were found associated with Callyspongia .

Description of female—Mean body length (excluding caudal setae) 593 µm and mean body width 173 µm. Body ( Fig. 1A ) cyclopiform with prosome slightly fusiform; urosome cylindrical. Cephalothorax with rounded epimera. Pedigerous somite with rounded epimera. Prosome length: width ratio= 1.9:1. Prosome: urosome ratio of length 1.2:1.

Urosome ( Fig. 1B ) four-segmented. Genital double-somite elongate, 110 × 83 µm, length: width ratio 1.3:1. First postgenital somite as long as wide (50 × 50 µm), length: width ratio 1:1; Second postgenital somite longer than wide (42 × 31 µm), length: width ratio 1.4:1. Caudal rami elongated, 55 × 16 µm armed with six setae. Egg sac not observed.

Antennule ( Fig. 1C ) slender 163 µm long (not including setae), 17-segmented. Length of segments measured along posterior to anterior margin: 22, 8, 13, 6, 4, 4, 5, 8, 7, 7, 6, 8, 9, 8, 9, 11 and 28 µm, respectively. Segmental homologies and setation as follows: 1(I)-2; 2( II)-2; 3( III – IV)-3; 4( V)-2; 5( VI)-1; 6( VII)-1; 7( VIII)-2; 8( IX – XIII)-4; 9( XIV)-1; 10( XV)-1; 11( XVI)-1; 12( XVII)-1; 13( XVIII)-1; 14( XIX)-1; 15(XX)-1; 16( XXI)- 1+ae; 17( XXII – XX- VIII)-11; all setae smooth. Aesthetasc on segment XXI 49 µm long.

Antenna ( Fig. 1D ) 195 µm long (including distal claw), with a basis of 51 µm long. Exopod 1-segmented, 8 µm long with two, one short and other long, distal setae. Endopod 2-segmented, the first segment 50 µm long, unarmed; second segment 15 µm long, with one strong seta on claw basis and a row of setules on inner margin, 62 µm long. Oral cone ( Fig. 1E ) 328 µm long, reaching somite of the fifth leg. Mandible comprised of sharp stylet ( Fig. 1F ), 283 µm long. Mandibular palp absent.

Maxillule ( Fig. 1G ) bilobed; inner lobe 22 µm long, armed with three setae and row of setules on inner margins. Outer lobe 8 µm long, armed with two setae. Maxilla ( Fig. 2A ) with syncoxa 69 µm long and long, curved claw 116 µm long. Maxilliped ( Fig. 2B ) 5-segmented, comprising syncoxa 27 µm long, unarmed; basis 63 µm long with one seta. Endopod 3-segmented, segments measuring 12, 25, and 24 µm, respectively; first segment unarmed; second segment with one seta; third segment bearing one seta near straight claw-like element, 95 µm long. Swimming legs 1-4 ( Fig. 2 C-D; 3A-B) biramous, with 3-segmented rami. The armature formula is as follows:

Third exopodal segment of legs 1-4 lacking one spine on outer margin. Second endopodal element of legs 1-3 with single inner seta. Coxa of legs 1-2 and basis of leg 1 with a row of setules on distal margin. Outer margins of coxa and basis of leg 3 and outer margin of coxa of leg 4 with setules. Distal angles of first and second endopodal segments of leg 2 with prominent teeth. Setae of leg 4 short and smooth.

Fifth leg ( Fig. 1B ) with free segment armed with three smooth setae. Somite five fused to genital double somite, bearing small seta near the insertion of P5 free segment.

Male. Unknown.

Etymology. The specific name ‘ spinoparva’ is a combination of ‘spine’ and the Latin term ‘parva’ (= few), referring to the absence of one spine on the lateral outer margin of the third element of legs exopods. The gender is feminine.

Remarks. The species of Scottocheres form three groups according to antennule segmentation. The first one includes Scottocheres longifurca , S stylifer , S. mipoensis , and S. youngi with an 18-segmented antennule; the second includes S. latus and S. stocki with a 19-segmented antennule ( Giesbrecht, 1897, 1902; Johnsson, 2002; Kim, 2016; Malt, 1991; Nicholls, 1944). The new species plus S. elongatus , S. gracilis , and S. laubieri form the third group with a 17-segmented antennule. ( Hansen, 1923; Johnsson et al., 2001).

Scottocheres spinoparva n. sp. has only two spines on the outer margin of the third endopodal element of leg 1, differing from S. elongatus and S. laubieri ( Johnsson et al., 2001) . Furthermore, the new species can also be distinguished from S. laubieri by the absence of setae on the first endopodal segment of the maxilliped ( Johnsson et al., 2001). Additionally, S. spinoparva n. sp is unique in the genus by showing only one seta on the inner margin of the second endopodal segment of legs 1 to 4.

Distribution. Scottocheres is a cosmopolitan genus with records on the Antarctic, Tropical Atlantic, North Atlantic and Pacific Oceans. These species were also recorded on the Mediterranean, North and Japan Seas ( Figure 3 ). Johnsson (2001) recorded S. elongatus and S. laubieri in Pincinguaba, littoral of S„o Paulo state. Later, he recorded S. laubieri in California Reef on the archipelago of Abrolhos, where he also found the first Brazilian species, S. youngi , associated with the sponge Monanchora sp. Carter, 1883 ( Johnsson, 2002). Scottocheres spinoparva n. sp. represents the second Brazilian species and was found in association with a sponge of genus Callyspongia collected on Todos-os-Santos Bay ( Table 1 ).

Figures

FIGURE 1. Scottocheres spinoparva n. sp., female (paratype: UFBA 3267).A, habitus, dorsal view; B, urosome; C, antennule; D, antenna; E, siphon; F, mandible stylet; G, maxillulle; H, maxilla; I, maxilliped. Scale bars: (A) 100 µm; (B) 50 µm; (C, D, H, I) 25 µm; (E, F) 5 µm; (G) 10 µm.

FIGURE 2. Scottocheres spinoparva n. sp., female (paratype: UFBA 3267). A, leg 1; B, leg 2; C, leg 3; D, leg 4. Scale bars: (A–D) 25 µm.

FIGURE 3. Scottocheres species cosmopolitan distribution. 1, Antarctic Ocean; 2, Pincinguaba—Brazil; 3, California Reef, Abrolhos—Brazil; 4, Todos-os-Santos Bay—Brazil; 5, South West of Iceland; 6, Moray Firth—Scotland; 7, Banyuls—France; 8, Gulf of Naples—Italy; 9, Chik Chau—Hong Kong; 10, Japan Sea—South Korea; 11, Sellick Reef—Australia.