Stenoniscus nestori López-Orozco, Taiti & Campos-Filho sp. nov.

urn:lsid:zoobank.org:act: 045F7904-E6DE-4912-9073-1473A522FAC7

Figs 1, 2C, 6–8

Etymology

The new species is named after Dr Nestor Hernando Campos, for his contribution to the knowledge of Crustacea from Colombia.

Material examined

Holotype COLOMBIA – Bolívar, Cartagena de Indias, Islas del Rosario, Isla Grande • ♂ (parts in micropreparations); La Punta, Laguna Encantada; 10°10′48.1″ N, 75°43′37.5″ W; 7 Sep. 2017; C.M. López-Orozco, R. Borja-Arrieta and Y.M. Carpio-Díaz leg.; CUDC-CRU 185.

Paratypes COLOMBIA – Bolívar, Cartagena de Indias, Islas del Rosario, Isla Grande • 1 ♂, 1 ♀ (parts in micropreparations); same collection data as for holotype; CUDC-CRU 186 • 2 ♀♀; same collection data as for holotype; CUDC-CRU 187 • 1 ♀; same locality and collectors as for holotype; 24 Aug. 2017; CUDC-CRU 188 .

Description

MEASUREMENTS. Maximum body length: male 1.8 mm; female 2.4 mm.

BODY. Body pigments absent (Fig. 2C). Body (Fig. 6A–C) slender, about four times as long as wide, parallel sides. Dorsal surface bearing ribs and tubercles (Fig. 6A–C, E–G), as follows: cephalon with two tubercles on anterior portion and three on posterior portion; pereonite 1 with two transversal ribs; pereonites 1–4 with three longitudinal ribs (middle rib split in two on pereonites 2 and 3), one lateral tubercle and one tubercle between two lateral ribs per side; pereonites 5–7 with two longitudinal ribs and one lateral tubercle per side; pleonites 2–5 and telson with two paramedian tubercles. Dorsum bearing rectangular scale-setae with fringed apex (Fig. 6D).

CEPHALON. Sub-rectangular (Fig. 6E–F), median lobe triangular, lateral lobes well-developed, directed frontwards, not surpassing median lobe; eyes absent.

PEREON. Epimera of pereonites 2–7 laterally grooved (Fig. 6B). Pereonites 4–5 ventrally with lateral sternal thickenings small, triangular; pereonites 6 and 7 ventrally with sub-rectangular sternal plates (Fig. 6C).

PLEON. Pleonite 2 dorsally visible, 3–5 with rectangular epimera (Fig. 6A–C). Telson (Fig. 6G) trapezoidal, distal margin broadly rounded.

ANTENNULA. Composed of two articles (Fig. 6H), proximal article stout with shield-like projection on distal margin, distal article comma-shaped bearing two distal aesthetascs.

ANTENNA. Short (Fig. 6I), peduncle articles more or less subequal in length; flagellum of two articles, distal article twice as long as proximal article, bearing two lateral aesthetascs.

MOUTH. Mandibles with molar penicil consisting of two plumose setae, left mandible (Fig. 7A) with two penicils on incisor process, right mandible (Fig. 7B) with one penicil. Maxillula (Fig. 7C) inner endite with two short apical penicils; outer endite bearing 4+4 teeth, inner set with two teeth apically cleft. Maxilla (Fig. 7D) of two rounded lobes, inner lobe bearing three thick setae. Maxilliped (Fig. 7E) basis with sparse setae; endite stout, distal margin rounded, bearing thin setae, one large penicil inserted near medial margin.

UROPOD. Protopod stout and conical, exopod short, bearing two long apical setae, endopod inserted proximally (Fig. 7F).

PEREOPODS. Pereopods 1–7 short, stout, merus to propodus bearing sparse setae on sternal margins; pereopod 1 carpus with distal seta fringed at apex; dactylus of two claws, inner claw very short, ungual seta simple, not surpassing outer claw, dactylar seta stout, reaching distal margin of outer claw, apex bearing many small setae.

Male

PEREOPODS 1 AND 7. Without sexual dimorphism (Fig. 8A–B).

PLEOPODS. Pleopod 1 exopod absent; endopod (Fig. 8C) enlarged on proximal portion, distal portion tapering. Pleopod 2 (Fig. 8D) exopod triangular, inner margin grooved, bearing one strong seta; endopod about twice as long as exopod. Pleopod 3 and 4 exopods (Fig. 8E–F) sub-quadrangular, inner margin grooved, distal margin slightly serrate. Pleopod 5 exopod (Fig. 8G) sub-rectangular, inner margin slightly serrate, distal margin straight, bearing one seta.

Remarks

Presently, Stenoniscus comprises four species (Schmalfuss 2003): S. pleonalis Aubert & Dollfus, 1890 from the northern coasts of the Mediterranean east to the Aegean, Bermuda, Bulgaria, Madeira and Mexico; S. carinatus Silvestri, 1897 from coastal areas of Croatia, Italy, Portugal and Spain; S. aenariensis (Verhoeff, 1942) and S. plutonis (Verhoeff, 1942) from Ischia Island, Italy, both most probably junior synonyms of S. pleonalis according to the short descriptions by Verhoeff (1942). The genus can be defined by animals of reduced size (up to 3.5 mm), body slender with lateral sides parallel, dorsum bearing longitudinal ribs and tubercles, sometimes reduced, epimera of pereonites 2–7 with lateral margins grooved, pereonites 4–5 ventrally with lateral sternal thickenings and 6–7 with sternal plates, antennula of two articles, pleonite 1 absent, uropods of conical shape, pleopod exopods without respiratory organs, and pleopod 1 absent on females (see Vandel 1962; Schmidt 2003).

Stenoniscus nestori López-Orozco, Taiti & Campos-Filho sp. nov. is morphologically similar to Stenoniscus carinatus, from which it differs mainly in the number and disposition of the dorsal ribs and tubercles on the cephalon and pereonites (compare Fig. 6A–B with Schmidt 2003: fig. 67 and Taiti & Ferrara 1982: fig. 6a for S. carinatus). The new species is readily distinct from Stenoniscus pleonalis in having a strong dorsal ornamentation (vs very weak) and lacking the tomentose appearance due to long dorsal scale-setae (see Vandel 1944: fig. 1a–c).

Distribution

Presently known only from Isla Grande, Cartagena de Indias, Colombia.