Microprosthema pernambucensis

Microprosthema pernambucensis (Bochini, Cunha, Terossi & Almeida, 2020) (Figs. 1–3, 5a–c) Chicosciencea pernambucensis Bochini, Cunha, Terossi & Almeida, 2020: 706, figs. 1–5. Microprosthema pernambucensis. — Anker & Goy 2023: 406. Material examined. Republic of Cabo Verde, west coast of Sal Island: 1 female (pocl 2.2 mm), dive site Palmeira 4, depth 14 m, in crevice in rock wall of lava tube, leg. P. Wirtz, 18 Sept. 2021, RMNH. CRUS. D.59342; 1 ovig. female (pocl 3.3 mm), 2 females (pocl 3.2, 3.5 mm), dive site Palmeira 4, depth 15 m, in crevice in rock wall of lava tube, leg. P. Wirtz, 18 Sept. 2021, RMNH. CRUS. D.59343; 3 ovig. females (pocl 2.6–3.5 mm), 1 female (pocl 3.2 mm), dive site Palmeira 4, depth 16 m, in crevice in rock wall of lava tube, leg. P. Wirtz, 10 Sept. 2021, RMNH. CRUS. D.59344; 1 female (pocl 3.3), dive site Palmeira 4, depth 15 m, in crevice in rock wall of lava tube, leg. P. Wirtz, 14 Sept. 2021, RMNH. CRUS.D.59338. Description. Rostrum (Fig. 1a–c, s) falling short of mid-length of scaphocerite, 0.3–0.4 of carapace length, robust, straight or slightly descending, proximally widening, without supraorbital eaves; tip acute; dorsal carina armed with 6–7 acute, anteriorly directed teeth of approximately same size, distal portion unarmed; ventral carina armed with 2 anteriorly directed, acute teeth located between 0.7 and 0.8 of rostral length; lateral carinae weakly developed, unarmed. Carapace with post-rostral median ridge poorly developed, unarmed, short (Fig. 1b); carapace surface and anterior margin sparsely covered with denticles, all anteriorly directed, sharp or weakly subacute; orbital margin (Fig. 1a) concave, inferior orbital angle obsolete; antennal tooth small, acuminate; pterygostomial region with 5–6 small marginal teeth (Fig. 1d, s); cervical groove (Fig. 1a) distinct, shallow; posterior crest low, armed with series of small teeth overhanging cervical groove; hepatic, branchial and post-cervical regions sparsely ornamented with denticles of varying sizes (Fig. 1a, b, s). Pleon (Fig. 1e) feebly sculptured; pleonite 2 with 2 transverse, shallow, linear grooves, postero-ventral margin armed with small tooth; pleonite 3 with single, transverse groove, postero-ventral margin armed with small tooth; pleonites 4–5 with 2 and 3, respectively, marginal small teeth along ventral part of posterior margin; pleonite 6 unarmed. Telson (Fig. 1f, 3) relatively elongate, distinctly constricted near base, tapering distally, about 2.3–2.5 times as long as maximal width; dorsal surface with shallow, distally widening, median groove, flanked by 3 strong, acute, movable spines in distal half; additional acute, movable spines present on dorsal surface, as following: 1 pair of small spines proximally, several small, scattered spines medially, and 1 pair of stronger spines near basal constriction; each lateral margin armed with single, sharp tooth at about 0.5 of telson length; posterior margin convex, armed with 1 pair of subacute teeth at posterolateral angle and 1 somewhat stronger medial tooth. Eyes (Fig. 1g) well developed; cornea hemispherical, facetted; eyestalk adorned with few denticles on dorsal and anterior surfaces. Antennular peduncle (Fig. 1a, b) not reaching mid-length of scaphocerite; 1 st article subequal in length to 2 nd and 3 rd articles combined; stylocerite blunt distally, strongly curved mesially; antennal flagella long, setose. Antenna (Fig. 1a, b, h) stout; basicerite armed with moderately developed distolateral tooth and 2 teeth on ventrolateral margin, mesial margin laminate; scaphocerite about 1.8 as long as greatest width; lateral margin straight, furnished with 5 teeth, ending in stout tooth, overreaching distal margin of blade; carpocerite short, falling short of antennular peduncle, feebly ornamented. Epistome (Fig. 1h) with 2 slender, anteriorly pointing processes. Mandible (Fig. 1j) robust; palp composed of 3 articles, distal article swollen, oval-shaped; molar and incisor processes separated. Maxillule (Fig. 1k) stout; endopod simple, distally tapering; coxal endite suboval, rounded, distal margin fringed with setae; basal endite of similar size, distally truncated, furnished with rows of stout, spiniform setae and more slender setae. Maxilla (Fig. 1l) with slender endopod; coxal and basal endites bilobed; scaphognathite well developed, ventral lobe short, semi-quadrate. First maxilliped (Fig. 1m) with biarticulated endopod; coxal endite bilobed; basal endite, large, subtriangular, with concave distal margin; exopod with well-developed flagellum; epipod large, distinctly bilobed. Second maxilliped (Fig. 1n) with distinct coxa; epipod slender, with well-developed, lamellate podobranch; endopod typical for genus; exopod with well-developed, long flagellum. Third maxilliped (Fig. 1o–q) with ischium compressed, distodorsal and distoventral angles armed with 2 and 1 small, sharp teeth, respectively, lateral margins unarmed; merus furnished with oblique row of teeth on mesial surface; carpus and propodus unarmed, subequal in length; dactylus tapering. First pereiopods (Fig. 2a, b) moderately slender, with all articles unarmed; ischium about 0.75 length of merus; merus about 0.8 length of carpus; carpus somewhat distally widening, about 1.4 length of chela, carpo-propodal brush well developed; palm subcylindrical; dactylus and pollex subequal in length, about 0.5 length of chela, cutting edges unarmed. Second pereiopods (Fig. 2c, d) longer than first pereiopod, with all articles unarmed; ischium about 0.45 length of merus; merus about 0.8 length of carpus; carpus somewhat distally widening, about 1.75 length of chela; palm subcylindrical; dactylus and pollex subequal in length, about 0.4 length of chela, cutting edges minutely serrated. Third pereiopods (Fig. 2e–g, n, o) robust, subequal in length and similar in shape and proportions; ischium about 0.6 length of merus, distodorsal angle with 1 well-developed subdistal tooth and 1 additional tooth in distal third of dorsal margin, mesial margin crenulate; merus about 1.2 length of carpus, dorsal margin with series of short teeth in proximal half, ventral margin with series of teeth throughout its length, increasing in size distally; carpus distally widening, about 4 times as wide as distal width, about 0.55 length of chela, dorsal margin armed with series of marginal and submarginal teeth, distolateral area dentate or rugose; chela feebly swollen; palm somewhat subrectangular in cross-section, about 2.5 times as long as greatest height, mesial and lateral surfaces sparsely rugose, ventral margin unarmed, dorsal margin variously dentate (Fig. 2f, m) in distal half; pollex and dactylus similar in length, about 0.3 length of chela, ventral surface of pollex and dorsal surface of dactylus unarmed, cutting edge of pollex proximally with 2 large teeth separated by large gap, distal half minutely serrated; dactylus with 1 large tooth approximately at mid-length, fitting into gap on pollex, distal half minutely serrated. Fourth pereiopod (Fig. 2h–j) long, slender; ischium about 0.4 length of merus, unarmed; merus about 0.75 of carpus length, unarmed; carpus about 1.8 length of propodus, weakly subdivided (with incomplete, suture-like articulations) into 4 subarticles, distal angle on flexor margin with single spiniform seta; propodus not subdivided, flexor margin armed with row 10–12 spiniform setae; dactylus compressed, about 0.25 length of propodus, strongly biunguiculate. Fifth pereiopod (Fig. 2k, l) similar to 4 th pereiopod in proportions; carpus weakly subdivided into 6 subarticles; propodus not subdivided, flexor margin armed with row of 12–15 moderately spaced, spiniform setae. First pleopod uniramous, short; 2 nd to 5 th pleopods biramous, decreasing in size posteriorly. Uropod (Fig. 1r) with stout, distally bifid protopod; exopod broad, barely overreaching distal margin of telson, equal in length to endopod; lateral margin relatively straight, with 6–7 serrations; distolateral angle formed by posterior-most serration/tooth; distal margin broadly rounded; dorsal surface with 2 subparallel carinae; endopod ovoid, slightly tapering distally, lateral margins unarmed; dorsal surface with single, unarmed, longitudinal carina. Colour pattern. Body semi-translucent (Fig. 5a–c); carpus, propodus and chela of 3 rd pereiopod reddish, fingers white; gastric region of carapace red; 1 st and 2 nd pleonites with incomplete, transverse red bands; third pleonite with oval-shaped red patch on dorsal surface; 4 th to 6 th pleonites with transverse red bands; proximal part of telson and uropods with transverse red band. Distribution and ecology. Currently known only from two disjunct localities in the Atlantic Ocean: Pernambuco (Tamandaré and Cabo de Santo Agostinho), north-eastern Brazil, the type locality (Bochini et al. 2020), and the western coast of Sal Island, Cabo Verde (Cape Verde) (present study). The Brazilian type material was extracted from “artificial refuge structures” placed at a depth of 4.4–4.5 m on a sandstone reef (Bochini et al. 2020), whereas the Cape Verdean specimens were collected inside subtidal lava tunnels at depths of 14– 16 m. Remarks. Despite an initial assumption that the Cape Verdean material represented a new species, it is herein assigned to Microprosthema pernambucensis, because following a reexamination of two paratypes of that species (see below), no substantial species-level morphological differences nor significant discrepancies in the colour pattern could be detected. As already pointed out by Goy (2023), the description and illustrations of M. pernambucensis in Bochini et al. (2020) are problematic, being too small and diagrammatic (figs. 2, 5), erroneous (fig. 5B, E, F), or non-informative (figs. 3B–D, 4). Perhaps the most important error in Bochini et al. (2020) is the description of the telson, which is stated to have the “posterior margin rounded…free of spines”; supported as such by a schemat