Parapseudomma stenurum Wittmann 2023, n. sp.
Creators: name: Wittmann, Karl J.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Mysida
Mysidae
Parapseudomma
Parapseudomma stenurum

description: Parapseudomma stenurum n. sp.
(Figs. 3–6)
https://zoobank.org/ urn:lsid:zoobank.org:act: 4FC 1ECE8-5E91-4246-B078-311A9E9F91CE
Parapseudomma calloplura — Wittmann, 2020: 18, 19, tab. 1.
Typematerial. Holotype:adult female(BL 24.9 mm) completely dissected, on 12 slides numbered in series of RMNH. CRUS.21840 to RMNH. CRUS.21851, Cape Verde Islands, S of Santiago, DD 14.517 -023.55, 3825–4025 m depth, deep-sea clay, 3.5 m Agassiz trawl, expedition CANCAP-VI, sta. 6.018, 5 June 1982. — Paratypes: 1 adult female (BL 20.0 mm), 1 juvenile, fragments of 1 immature, ZMH 58263, Angola Basin, start DD 22.3323 003.3057, end DD 22.3375 003.3073, 5179– 5179 m depth, n.n., #318, 9 July 2000. — 1 adult female (BL about 23.3 mm), head broken, ZMH 58264, Angola Basin, start DD 22.3319 003.2993, end DD 22.3342 003.2993, 5161–5162 m depth, n.n., #320, 10 July 2000. — 2 damaged immatures (BL ca. 6.1, 7.0 mm), ZMH 58266, plus separate vial with 1 immature female (BL 9.4mm), ZMH 58265, Angola Basin, start DD 17.0823 004.6801, end DD 17.1242 004.7046, 5460– 5460 m depth, n.n., #344, 25 July 2000. — 1 subadult female (BL 21.1 mm) plus 1 subadult female (BL about 14 mm) with tailfan missing, ZMH58267,same sample as before, s.n. — 1 subadult female (BL 17.2 mm), ZMH58268, same sample as before,e.n. — 1immature male (BL 11.2 mm), ZMH 58269, Angola Basin, start DD 16.2222 005.4473, end DD 16.2470 005.4450, 5433–5434 m depth, e.n., #350, 29 July 2000.
Diagnosis. Based on adult females. All female features within the limits of the genus diagnosis. Carapace with rounded disto-lateral edges; rostrum short and broadly rounded (Fig. 4F), slightly uptilted (Fig. 3C). Eye rudiments fused at proximal half (of antero-posterior extension), distally separated by narrow median cleft (Fig. 3D). Transverse extension of eye-bar 1.8–2.5 times length of distal segment of antennular trunk. Eye rudiments dorsoventrally f lattened by factor of 1.6–1.8 measured at maximum antero-posterior extension in dorsal view; anterior margin not serrated. Disto-mesial lobe dorsally at basal segment of antennular trunk reaching to distal margin of median segment. Disto-lateral edge of antennal sympod angular, no tooth-like projection. Antennal scale not subdivided, no apical lobe (Fig.5C). Length of scale 3.4–3.6 times maximum width. Scale extends 50–60% its length beyond antennal peduncle and 50–70% beyond antennular trunk. Labrum mid-anteriorly slightly produced, tip rounded (Fig. 5E). Mandibles with pars incisiva, pars centralis and pars molaris well developed; right digitus mobilis reduced to slender spine (Fig. 4B), left digitus essentially normal, though more slender than in most mysids (Fig. 4A). Carpopropodus of thoracic endopods 3–8 with 2–3 segments separated by transverse articulations. Endopod of uropods without spine (Fig.3F). Telson (Figs. 3F, 4D, 6K)elongate trapezoid, slender, with slightly sigmoid, almost straight lateral margins. Telson length 2.7–3.0 times maximum width near basis and 10–14 times width at disto-lateral edge; narrow terminal margin convex. Proximal 23–25% of lateral margins smooth, remaining distal portion of each margin with 17–23 spines distally somewhat discontinuously increasing in size; terminal margin with 3–4 pairs of large spines. Terminal spines bilaterally lined by minute stiff bristles along basal 50–70% of their margins (Fig. 4D); largest spine one seventh telson length; no unpaired median spine.
Description of the holotype. All female features within the limits of the species diagnosis. Female with 24.9 mm body length, marsupium empty (Fig. 3A). Rostrum contributing 0.6% to body length, carapace 23% (without rostrum), thorax 32%, pleon 49%, and (long) telson 19%. Parts of body cuticle ornamented with fields of minute, roughly ellipsoidal shallow depressions (Fig. 4C), some of which (accidentally) filled with external material. Tergites of thoracomere 8 and of adjoining pleomeres 1, 2 almost completely ornamented, carapace mainly on fields illustrated as shaded areas in Fig. 5D. Minor numbers of such depressions present on antennular trunk and antennal peduncle, again fewer on basal plates of thoracic exopods. Minute ‘cils’(4–7 µm long slender scales) line outer margin and parts of dorsal face of eye rudiments.
Carapace (Fig. 5D) with disto-lateral edges well rounded. Cervical sulcus distinct, no cardial sulcus visible. Posterior margin weakly concave. Carapace leaving 1.5 thoracic segments mid-dorsally exposed (as in other mysids the coverage may vary with swelling of the thorax due to yolk accumulation in the ovarian tubes).
Antennula(Figs.3B, 5A,B).Transversearticulations between three segments of trunk. Segments 1–3 contributing 49%, 22%, and 29% to total trunk length, respectively. Setose lobe dorsally in about median position shortly behind anterior margin in each segment. Median lobe of distal segment with 3 barbed setae and transverse series of 3 teeth (Fig. 5B). Tooth size increasing laterally. Basal portion of outer flagellum 0.8–0.9 times as wide as in inner flagellum.
Antenna (Figs. 3B, 5C). Sympod two-segmented, caudally in addition with end sac of antennal gland. Peduncle with 3 segments separated by transverse articulations.Basal segment contributing 30%,median segment 43%, and terminal segment 27% to total length. Basal segment smooth, median and terminal segments each with few barbed setae.
Labrum as in diagnosis and in Fig. 5E, damaged labium as in Fig. 5G, mounting of foregut failed.
Mandibles (Figs. 4A,B, 5F). Palp three-segmented with basal segment contributing 12–13%, median segment 62–63%, and terminal segment 24–26% to total palp length. Palp not hispid, its basal segment without setae, median segment with sparse setation on both lateral margins. Length of median segment 4 times maximum width, lateral margin slightly sigmoid while mesial margin sigmoid with near-median convex portion more strongly curved than proximal concave portion. Terminal segment 2.3–2.9 times as long as broad and 0.4 times as long as median segment. Terminal segment well setose, with longitudinal series of setae on distal 3/4 of rostral face. Right mandible (Fig. 4B) with 5 large teeth on pars incisiva; digitus mobilis reduced to slender, subapically slightly microserrated spine; pars centralis with large spinefree portion proximally followed by large lobe apically bearing seven long spines; these spines microserrated by acute bristles along their subbasal to subapical portions. Processus molaris of each mandible with strongly cuticularized masticatory lamellae. Left mandible (Figs. 4A, 5F) normal, its pars incisiva with 4 large teeth; digitus mobilis with long, slender basis and with 2 large, plus more than 4 small teeth on apex; pars centralis all along with 12 slender spines bearing stiff bristles (only 4 spines roughly in focus in Fig. 4A, all 12 spines visualized in Fig. 5F).
Maxillula (Fig.5H). Distal segment with 15 strong, bluntly serrated spines on transverse terminal margin. This segment subterminally with transverse series of 9 setae bearing long stiff barbs. Basal segment furnished with mainly longitudinal though basally bent, comparatively long series of densely set long hairs. Endite terminally with 3 large, distally spiny (by stiff bristles) setae flanked by shorter barbed setae. Two most proximal setae of endite much longer and more slender compared with their distally neighboring setae.
Maxilla (Fig. 5I) densely setose, without spines. Sympod with 3 mesial, only distally strongly setose lobes. Exopod extending to distal margin of basal segment of palp. Exopod with numerous plumose setae all along lateral margin; longest seta at tip, mesial margin with only 3 much shorter plumose setae in subapical position. Palp two-segmented, apical segment 1.1 times as long as basal segment. Apical segment 1.8 times longer than maximum width. Its transverse terminal margin densely setose, lateral margin sparsely setose, mesial margin with only 2 setae near disto-mesial edge. Basal segment basally broader, on rostral face(below drawing plane in Fig.5I) near mesial margin with longitudinal series of 7 densely barbed, basally thick setae (visualized by dashed lines).
Thorax(Fig.6A–H).Sternite 1with distally rounded mid-rostral lobe. Sternites 2–8 without mid-ventral processes. Basal plates of exopods 1, 8 with length twice maximum width;plates2–7with twice maximum width. Disto-lateral edge with small tooth-like projection in all basal plates. Flagellum of exopod 1 with 8 segments, flagella 2–8 with 9 segments. Endopods 1, 2 with 6 segments, endopods 3–8 broken.
Sympod of thoracopod 1 (Fig.6A)with small mesial lobe bearing 1 plumose seta at tip. Basis of endopod 1 with very large setose endite, remaining segments without endite. Endopod 1 densely setose along mesial margin, less along lateral margin; its smooth apical nail (Fig. 6B) 1.6 times as long as dactylus. Epipod 1 (Fig. 6A) linguiform with narrowly blunt apex, length 0.9 times that of basal plate of exopod 1. Epipod subapically with 3 minute setae.
Endopod 2 (Fig. 6C, D) without endites. Two very long setae reaching from disto-mesial edge of basis beyond ischium. Dactylus reflexed, densely setose, remaining segments less setose. Dactylus with short thick nail (Fig. 6D) hidden in the dense jungle of setae.
Marsupium (Figs. 3A, 6H). Proximal portion of oostegite 1 with dense brush of setae on inner face (inside marsupium). These comparatively long setae microserrated by series of stiff, acute bristles along their distal half. Less dense brush of such setae on oostegite2, again less dense on oostegite 3.Oostegite 1 with small smooth setae along most of ventral margin and on distal half of dorsal margin, the latter margin partly folded inward (artificially) in Fig. 6H. Coverage by tiny hairs on and near dorsal margin. Shaded fields in Fig. 6H visualize areas with minute acute scales. Most of dorsal margin smooth in oostegites2, 3. These oostegites with ventral and anterior margins plus part of posterior margin bearing barbed setae contributing to ventral and caudal, ventilation-pervious closure of marsupium. Only oostegites 2, 3 with smooth, slender whip setae loosely scattered over most of outer face; no scales on both faces.
Pleon including tail fan (Figs. 3A, F–H, 6I–K). Pleonites 1–5 measuring 0.5–0.6 times length of pleonite 6; the value being 1.4 for exopod of uropods, 1.3 for endopod, and 1.2 for telson. Both length and slenderness of pleopods 1–5 increasing caudally, setation as in Fig. 6I, J. Scutellum paracaudale subtriangular, distally continuously rounded. Exopod of uropods extending 0.1 times its length beyond endopod and 0.2 beyond telson; endopod0.1 times its length beyond telson (Fig. 3F). Statoliths composed of fluorite, diameter 0.18–0.19 mm. Telson with total of 41 spines, comprising 17 plus 18 small smooth spines on lateral margins along with 2 × 3 large, hispid spines on terminal margin.
Supplementary data from paratypes. All paratypes stem from the deep sea of the Angola Basin.Immature male with BL 11.2 mm showing right mandible as in holotype (Fig. 4B). Its left mandible also as in the holotype (Fig. 4A) except for two meristic differences, namely digitus mobilis with 2 large plus 3 (versus> 4) small teeth on apex and pars centralis all along with 8 (versus 12) slender spines.
Immature female with BL 9.4 mm showing hispid, anteriorly curved, median processes from thoracic sternites 4–8 (nos. 1–3 not inspected). No such processes in adult females. Immature male with BL 11.2 mm with such processes on sternites 2–8, its penes extending shortly beyond sympod 8, appendix masculina still very small; pleopods 1–5 still uniramous (Fig. 3G) with pseudobranchial lobe larger than in female holotype; pleopods 1–3, 5 unsegmented, increasing in length caudally; pleopod 4 not in series by being the largest (Fig. 3G), distally with incipient segmentation(Fig. 3H). No additional males available.
Thoracic endopods 3–8 of both sexes with 7–8 segments (Fig. 6E) counting from basis to dactylus or 6–7 segments (Fig. 6F) from praeischium to dactylus, respectively. Carpopropodites with 2–3 segments separated by transverse articulations (Fig. 6E, F). Dactyli with slender,weakly bent,smooth nail(Fig.6G).
Statoliths mineralized with f luorite, diameter 0.13−0.17 mm (n = 4 statoliths of two adult females).
Etymology. The species name is an adjective with Latinized neutral ending formed by amalgamation of the Classic Greek adjective στενός (narrow) with the noun ουρά (tail) referring to the slender telson.
Typelocality. E-Atlantic, Cape Verde Islands, about 42 km south of Santiago Island, DD 14.517 -023.55, on the sea floor in 3825–4025 m depth.
Distribution. E-Atlantic, Cape Verde Islands and Angola Basin, total ranges 14°N to 22°S, 05°E to 24°W, depth 3825–5460 m.
description: Published as part of Wittmann, Karl J., 2023, The genus Parapseudomma from the East Atlantic deep sea, with description of a new species (Mysida: Mysidae), pp. 1-17 in Nauplius (e 2023013) (e 2023013) 31 on pages 8-14, DOI: 10.1590/2358-2936e2023013, http://zenodo.org/record/10905080