Cymbasoma clauderazoulsi, Suárez-Morales & Goruppi & de Olazabal & Tirelli, 2017

Suárez-Morales, Eduardo, Goruppi, Alenka, de Olazabal, Alessandra & Tirelli, Valentina, 2017, Monstrilloids (Crustacea: Copepoda) from the Mediterranean Sea (Northern Adriatic Sea), with a description of six new species, Journal of Natural History (J. Nat. Hist.) 51 (31 - 32), pp. 1795-1834 : 1811-1814

Cymbasoma clauderazoulsi sp. nov.

( Figure 6 (a – i))

Material examined

Adult holotype female from station 8, harbour of Trieste, North Adriatic Sea ( Figure 1 , Table 1), partially dissected, appendages mounted on slide in glycerine, sealed with Entellan®. Date of collection: 4 May 2016. Slide deposited in ECO-CHZ-009524.

Description of adult female

Body elongated, slender ( Figure 6 (a, b)); body length of holotype female 1.28 mm. Cephalothorax 0.82 mm long, representing 64% of total body length. Midventral oral papilla located at 25% of cephalothorax length. Pair of relatively small ocelli present, pigment cups moderately developed, medially separated by one eye diameter, weakly pigmented; ventral cup larger than lateral cups ( Figure 6 (a, c)). Cephalic area with weakly produced ‘ forehead ’, ornamented with shallow transverse striations ( Figure 6 (c)) and pair of sensilla. Wide, dorsal symmetrical rounded protuberances surrounding ocelli (arrowed in Figure 6 (c)) and adjacent lateral expansions in cephalic section. Low ventral rounded protuberance with adjacent transverse striae (arrows in Figure 6 (d)). Additional cephalic cuticular ornamentation including transverse, shallow cuticular striation overlying anterior ventral surface of oral papilla ( Figure 6 (j)). Pair of symmetrical nipple-like processes on anterior ventral surface at each side of oral area ( Figure 6 (j)).

Urosome consisting of fifth pedigerous somite, genital double-somite and anal somite, together representing 10% of total body length. Relative lengths of urosomites (fifth pedigerous, genital-double and anal somite) as: 36.1: 41.3: 22.6 = 100, respectively. Genital double-somite with smooth dorsal and ventral surfaces, with rounded posterior process on lateral margin, visible in dorsal view (arrows in Figure 6 (f, g)); insertion of ovigerous spines with adjacent curved row of slender, short spinules. Caudal ramus subquadrate, armed with three subequally long, sparsely setulated caudal setae ( Figure 6 (h)). Ovigerous spines paired, relatively short (0.28 mm), representing 21% of total body length ( Figure 6 (b)). Spines basally separated, slender, straight at their base and along shaft, without distal expansions and tapering distally, spines subequally long ( Figure 6 (i)).

Antennule length 0.34 mm, relatively long, remarkably divergent, representing about 25.6% of total body length and 41% of cephalothorax length ( Figure 6 (a)). Antennule 4- segmented, segments 3 – 4 completely fused; intersegmental division between these segments marked by elongated, relatively narrow section. Distal antennulary segment longest, representing 49% of antennule length. In terms of pattern described by Grygier and Ohtsuka (1995) for female monstrilloid antennulary armature, setae (Roman numerals) and spines (Arabic numerals), stout, spiniform element 1 present on first segment; elements on second segment: 2d1-2, 2v1-3 and IId. Third segment with slender, long element 3 plus elements IIId and IIIv. Segment 4 bearing elements 4d1,2, 4v1-3; setae IVd, IVv, Vd, Vm present. Element 5 spiniform, short. Subterminal elements b1-6 present, unbranched; elements 61 – 2 and 6aes present in specimens ( Figure 6 (e)).

Incorporated first pedigerous somite and succeeding three free pedigerous somites each bearing a pair of biramous legs. Pedigerous somites 2 – 4, together accounting for 17% of total body length in dorsal view. Legs 1 – 4 slightly increasing in size posteriorly. Intercoxal sclerites of legs 1 – 4 subrectangular, widest at base, tapering distally, surface and posterior margin smooth. Bases of legs 1 – 4 articulating with large, rectangular coxa along oblique line; with outer basipodal seta; on leg 3, this seta about 2.2-times longer, slightly setulated from proximal half and slightly thicker than those on the other legs. Endopods and exopods of legs 1 – 4 triarticulated. Ramal setae all biserially plumose except spiniform outer seta on exopodal segments 1 and 3, and inner seta of first exopodal segment, these latter being short, slender and sparsely setulated. Spine on distal exopodal segment of right leg 4 acute; outermost apical exopodal setae of legs 1 – 4 with inner margin sparsely setulated, outer margin spinulose ( Figure 6 (k)). Armature formula of legs as in previous species.

Fifth legs medially conjoined, bilobate, inner (endopodal) lobe elongate, thumb-like, unarmed, rounded distally, reaching about ¾ the length of outer lobe. Outer (exopodal) lobe elongated, slender, armed with two long setae on distal position plus short, slender innermost seta ( Figure 6 (h)).

Male. unknown.

Type locality

Harbour of Trieste , North Adriatic Sea (45°39 ʹ 06.08 ” N, 13°45 ʹ 22.63 ” E) ( Figure 1 ) .

Etymology

The species is warmly dedicated to Dr Claude Razouls, an esteemed French copepodologist who has created and constructed, for over 30 years, a comprehensive database and site on the Diversity and Geographic Distribution of Marine Planktonic Copepods (http://copepodes. obs-banyuls.fr), thus making a very valuable, solid contribution to the discipline worldwide.

Remarks

This species resembles the female of the previously described congener C. pseudobidentatum sp. nov. in the presence of: (1) the same fifth leg structure and armature, with the outer lobe armed with two long subequal setae and a minute innermost seta; (2) similar body proportions, with a cephalothorax representing 60 – 64% of body length; (3) diverging antennules representing 25% of body length; and (4) a similar shape and proportion of the genital compound and anal somites, particularly with a pair of posterolateral processes. There are, however, several differences between these two species: (1) the different antennulary segmentation, with a distinctive elongated intersegmental section of segments 3 – 4 in the new species ( Figure 5 (e)), a character that is absent in C. pseudobidentatum ( Figure 4 (c)); (2) antennulary element 3 is relatively short, thick in C. pseudobidentatum and long, slender in the new species; also, element 2v 1 is remarkably long in C. pseudobidentatum , longer than all the elements of group 2v-d, whereas this element is shorter than other elements of the group in the new species ( Figure 6 (e)); (3) the shape and size of the posterolateral processes on the genital double-somite; these are small, subtriangular in C. pseudobidentatum ( Figure 4 (e)) and larger, widely rounded in the new species ( Figure 6 (f)); (4) the anal somite is ventrally produced in C. pseudobidentatum and flat in the new species, C. clauderazoulsi ( Figure 6 (g)); (5) the new species is smaller (0.78 mm) than C. pseudobidentatum (1.28 mm) and the cephalothorax shape is different in these species, the former with a narrower cephalic section and relatively smaller eyes ( Figure 6 (a)).

The fifth leg with an inner lobe present and an outer lobe armed with two long seta and an inconspicuous minute inner seta is present in C. nicolettae Suárez-Morales, 2002 , C. thompsonii ( Giesbrecht 1893; Sars 1921) and in records of C. rigidum ( Sars 1921; Wilson 1932; Isaac 1975) in which the innermost seta is slender and very small (i.e. less than half the length of the other setae). The new species can be distinguished from this group of species by the presence of the posterolateral processes on the genital double-somite, but also by other characters. Among these species, only the Mediterranean C. nicolettae ( Suárez-Morales 2002) has a long, divergent set of antennules and a similar fifth leg (with short innermost seta) and similar body shape and proportions. It differs from C. clauderazoulsi sp.n. in the mammiliform shape of the fifth leg inner lobe, thus diverging from the simple thumb-like condition observed in the new species. Also, the innermost seta is noticeably longer and more conspicuous in C. nicolettae ( Suárez-Morales 2002, figure 8) than in the new species. The antennulary structure is similar in both species, with an elongated intersegmental section between segments 3 – 4, but in C. nicolettae elements 3 (short, robust) and 2v 1 (shorter than other elements of group 2v-d) ( Suárez-Morales 2002, figures 5 and 6) differ from the elements observed in C. clauderazoulsi (both elements 3 and 2v 1 are long and slender, as described).

Figures

Figure 1. Location of zooplankton sampling stations in the Gulf of Trieste (Italy), where monstrilloid copepods were obtained during the surveyed period.

Figure 4. Cymbasoma pseudobidentatum sp. nov., holotype adult female. (a) habitus, dorsal view; (b) habitus, ventral view; (c) right antennule with armature, dorsal view; (d) cephalic region showing preoral ornamentation and oral papilla, lateral view; (e) urosome, dorsal view showing subtriangular small processes on posterior margin of genital double-somite (arrow); (f) urosome with fifth legs, lateral view; (g) urosome and fifth legs, ventral view; (h) fifth legs, ventral view, outer setae cut short; (i) intercoxal sclerites of legs 1–4, anterior view; (j) third exopodal segment of leg 3 showing apical elements. Scale bars: 200 µm (a, b), 50 µm (c–g), 25 µm (h–j).

Figure 5. Cymbasoma pseudobidentatum sp. nov., allotype adult male from Trieste. (a) habitus, dorsal view; (b) cephalic region and right antennule showing armature, dorsal view; (c) cephalic region showing preoral ornamentation and oral papilla, lateral view; (d) cephalic region showing preoral ornamentation, ventral view; (e) urosome, dorsal view; (f) same, ventral view showing genital complex with diverging lappets; (g) urosome, lateral view showing genital complex; (h) leg 1 with intercoxal sclerite; (i) leg 3 with intercoxal sclerite. Scale bars: 200 µm (a), 50 µm (b–i).

Figure 6. Cymbasoma clauderazoulsi sp. nov., holotype adult female. (a) habitus, dorsal view; (b) same, lateral view; (c) cephalic region showing frontal ornamentation, dorsal view; (d) cephalic region, lateral view, anteriormost ventral protuberance arrowed; (e) right antennule with armature, dorsal view; (f) urosome, dorsal view showing posterolateral rounded processes on genital doublesomite; (g) urosome and fifth legs, lateral view (fifth leg setae and ovigerous spines cut short); (h) urosome and fifth legs, ventral view; (i) terminal part of the ovigerous spines, ventral view; (j) oral papilla and adjacent cuticular ornamentation, lateral view; (k) third exopodal segment of leg 3. Scale bars: 200 µm (a, b), 50 µm (c, d, j, k), 100 µm (e–h).