Iphinoe daphne Mazziotti & Lezzi 2020, n. sp.

Iphinoe daphne n. sp.

Figures 2–5

Type material. Holotype (MZB21008) adult male, type locality Cesenatico (st. 21), Lat. 44.128090, Lon. 12.244960, depth 3 m., 3 km offshore, soft bottom, biocenosis SFBC, data collection May 2017; paratype (MZB 21009) adult female st. 18; paratype (MZB 21010) adult male st. 22; paratype (MZB 21011) adult male st. 19; paratype (MZB 21012) adult male st. 20; paratype (MZB 21013) preadult male st. 22; paratype (MZB 21014) preadult female st. 22; paratype (MZB 21015) ovigerous female st. 21; paratype (MZB 21016) ovigerous female st. 18; paratype (MZB 21017) ovigerous female st. 19; paratype (MZB 21018) ovigerous female st. 20; paratype (ZSMA20190394) adult male st. 23; paratype (ZSMA20190395) preadult male st. 22; paratype (ZSMA20190396) adult male st. 20; paratype (ZSMA20190397) adult male st. 19; paratype (ZSMA20190398) adult male st. 18; paratype (ZSMA20190399) ovigerous female st. 22; paratype (ZSMA20190400) preadult female st. 22; paratype (ZSMA20190401) ovigerous female st. 20; paratype (ZSMA20190402) ovigerous female st. 19; paratype (ZSMA20190403) ovigerous female st. 18; paratype (CRU2019-1) adult male st. 24; paratype (CRU2019- 2) preadult male st. 24; paratype (CRU2019-3) preadult male st. 24; paratype (CRU2019-4) preadult male st. 24; paratype (CRU2019-5) preadult male st. 22; paratype (CRU2019-6) ovigerous male st. 22; paratype (CRU2019-7) ovigerous male st. 22; paratype (CRU2019-8) ovigerous male st. 24; paratype (CRU2019-9) ovigerous male st. 24; paratype (CRU2019- 10) ovigerous male st. 24.

Other material examined. 4 adult males, 2 preparatory males, 20 ovigerous females, 11 subadult females, st. 15; 4 adult males, 6 ovigerous females, 4 subadult females, st. 16; 2 adult males, 2 ovigerous females, st. 18; 13 adult males, 9 preparatory males, 46 ovigerous females, 54 subadult females, st.19; 24 adult males, 12 preparatory males, 116 ovigerous females, 76 subadult females, st. 20; 6 adult males, 5 ovigerous females, 11 subadult females, st. 21; 30 adult males, 16 preparatory males, 158 ovigerous females, 65 subadult females, st. 22; 21 adult males, 26 preparatory males, 34 ovigerous females, 130 subadult females, st. 23; 12 adult males, 4 preparatory males, 44 ovigerous females, 22 subadult females, st. 24.

Etymology. The epithet daphne is a noun in apposition. The species is named after the vessel used during the sampling; Daphne is also the name of the first author’s Institute Department.

Diagnosis. Pointed pseudorostrum. Carapace is about twice as long as it is deep and a fifth of the total body length. Ratio CL/CD 2.2. Presence of two perianal setae and one aesthetasc on main flagellum of antenna 1. Adult male with serrated middorsal line and a sternal process tubercle of distinctly bifid apex.

Description of the holotype adult male (MZB21008).

Total length: 4.8 mm.

Carapace about twice as long as it is deep and a fifth of the total body length (Figure 2A). The ratio CL/CD is 2.2 (Table 4). Dorsal carina armed with 6 teeth: the first immediately after the eyelobe, then following a space, the other five close to each other. Pointed pseudorostrum. Eyelobe well developed, elevated in lateral view, with 3 lenses. Branchial siphon of medium length. Frontal lobe does not extend anteriorly, the length is a third of the carapace. Anterolateral angle rounded with a few small serrations below (Figure 2B). Five free thoracic somites; the first is visible dorsally and laterally. Abdomen longer than rest of body, abdominal somites have well developed sideplates and five pairs of pleopods. Integument over the whole body exhibits a distinct reticulation, polygonal shaped under the microscope (Figure 2C). Sternite of the second thoracic segment bears a tubercle with a distinctly bifid apex (Figure 4).

Antenna 1 article 1 shorter than the other two articles. Article 2 inclined on the basal article at an angle of 45°. Third article a little less than three quarters as long as the second. Main flagellum two short articles, distal article with one aesthetasc and one terminal seta. Vestigial accessory flagellum minute, with 2 articles and 3 small setae; distal article the shortest (Figure 2D).

Antenna 2 longer than body length (Figure 2A, 3D). The peduncle has 4 articles; articles 1 to 4 are unarmed; article 5 has rows of sensory setae along anterior margin; flagellum articles bear a single row of setae.

Labium has 6 apical stout distally bent flattened setae, numerous setules on both apical margin (Figure 3L).

Mandible pars incisiva has 3 teeth, the lacinia mobilis has 3 teeth, there are 11 setae between lacinia mobilis and pars molaris (Figure 3H).

Maxilla 1 inner endite has 9 stout, spiniform setae (some subdistally dentate setae) and 2 simple setae on medial and distal margin; the outer endite has 6 robust setae and 1 filament. (Figure 3I).

Maxilla 2 endites exceed the upper margin of protopod, inner endite has 9 microserrate setae; outer endite has 14 slender curved microserrate setae and 2 simple setae on distal margin, the protopod has apical robust setae and fine setae on distal and medial inner margin (Figure 3A).

Maxilliped 1 basis has a long endite with four apical, three simple setae and three stout setae, carpus has eight stout palmate setae on the medial margin, large propodus about 0.8 times the length of the carpus, two simple short setae and two long setae on the apical margin, a short dactylus with terminal two stout short setae (Figure 3C).

Maxilliped 2 basis has 1 pappose seta on medial margin; merus has 1 pappose medial seta; carpus is 1 and a half times the length of the merus, with 3 pappose setae on distal medial margin; propodus is as long as the carpus, there are 4 simple setae on the medial margin and 3 pappose setae on the distal lateral margin; dactylus is a third of the length of propodus with 6 terminal setae (Figure 3B).

Maxilliped 3 basis about 0.6 times as long as the entire maxilliped, the outer process almost reaches the merus, with two long plumose setae. There are other smaller setae on medial margin. There are several plumose setae on the merus distal margin. Ischium and merus are as long as the carpus and propodus put together (Figure 2E).

Pereopod 1 basis weakly arcuate, moderately longer than the rest of the limb, dully serrate on the outer edge. Merus twice as long as the ischium, carpus and propodus are the same length. Dactylus shorter than the propodus, ending with 5 long terminal simple setae (Figure 2F).

Pereopod 2 basis slightly shorter than remaining segments put together, with numerous plumose setae. Merus tooth as long as carpus; carpus tooth is two thirds of the length of the dactylus. One plumose seta on carpus internal distal corner (Figure 2G).

Pereopod 3 basis 0.4 of the entire length of pereopod, merus is twice the length of ischium bearing two long simple seta on medial margin, carpus has two setae on distal outer margin, carpus 1.5 times the length of merus, propodus is 0.3 of the length of carpus with a seta on distal outer margin, dactylus about one third of the length of pereopod (Figure 3E).

Pereopod 4 basis 0.2 entire length of the pereopod, merus 2.5 times the length of ischium, carpus 1.1 times the length of merus, three setae on distal outer corner, propodus 0.4 times the length of carpus length, one seta on distal outer corner, dactylus 0.5 the length of propodus, bearing a terminal seta and a shorter one (Figure 3F).

Pereopod 5 basis 0.3 of the entire length of the pereopod, merus 2.5 times the length of the ischium, carpus 1.5 times the length of the merus, three long setae on distal outer corner, propodus 0.2 times the length of the carpus, one seta on distal outer corner, dactylus is the same length as propodus, bearing a terminal seta the same length as dactylus (Figure 3G).

Uropod peduncle slightly longer than rami, armed with 30 setae on inner edge, arranged in two lines from the eighth seta onward. Pleonite 6 distally rounded with two short terminal setae. Uropod exopod two-articulated with 7 plumose setae on inner edge and 6 terminal setae. Endopod two-articulated: first article with 8 setae of different sizes, with the last one being the largest; the distal part of the second article is rounded with 15 setae increasing in length from proximal to distal part and 4 terminal plumose setae (Figure 2H).

Description of the paratype ovigerous female (MZB21015).

Carapace about two times as long as deep and a fifth of the total body length. Dorsal carina armed with 6–8 teeth: the first immediately after the eyelobe, then following a gap the others close to each other. Pointed pseudorostrum. The eyelobe is elevated in lateral view, bearing a small tooth. Branchial siphon is of medium length. Anterolateral angle is rounded with a few small serrations below (Figure 5A).

The basis length of maxilliped 3 about 0.6 times the length of the entire maxilliped, the outer process almost reaches the merus, with two long plumose setae, plus additional smaller setae on medial margin. Several plumose setae on ischium, carpus and merus distal margin. Ischium and merus longer than carpus and propodus put together. Dactylus shorter than propodus and has 3 apical setae (Figure 5B).

Pereopod 1 basis slightly longer than the rest of limb. Merus, carpus and propodus subequal in length. The basis end bears a plumose seta reaching the merus end. Dactylus shorter than the previous 3 articles and has 5 terminal setae (Figure 5C).

Pereopod 2 basis shorter than the other articles put together; basis, merus and carpus have plumose setae. Dactylus longer than propodus and carpus together (Figure 5D).

Pleonite 6 distally concave, pleotelson rounded with two short terminal setae.

Uropod peduncle slightly longer than rami, armed with 12 acuminate setae on inner edge. Rami subequal in length. Exopod two-articulated, with 8 long plumose setae and 6 terminal setae. Endopod two-articulated with proximal article shorter than distal. First article armed with 4 acuminate setae; second article armed with 9 acuminate setae increasing in length from proximal to distal, and with 2 terminal plumose setae (Figure 5E).

Remarks. This new Iphinoe species is similar to other species within the “ I. trispinosa group” (sensu Ledoyer, 1965), in particular I. armata, I. douniae and I. trispinosa. The basis of I. daphne ’s pereopod 1 is longer than the remaining articles put together, differently from I. armata. I. daphne differs from I. trispinosa in the seta formula of the uropod: 10;5+ 15 in I. trispinosa and 12;4+ 9 in I. daphne. Pereopod 2 carpus of I. daphne presents only 1 plumose seta, whereas there are 3 in I. douniae and 2 in I. armata. Furthermore, pereopod 2 merus and carpus of I. daphne are shorter than in I. armata, as is the merus seta.

An important diagnostic character that distinguishes I. daphne from other congeneric species is its sternal process: it has a distinctly bifid apex, whereas this is cup-like with 6–8 serrations in the distal border in I. armata. Further differences between these species are shown in synoptic Table 2. I. daphne and I. serrata both have a sternal process with a bifid apex. However in I. serrata the tubercle is more elongated and the tips of the apex are more divergent.

Distribution and ecology. The species was only recorded in the North Adriatic basin, Area 9 (Table 4), and was not present in samples collected from similar biocenosis (SFBC or VTC) in other areas, thus suggesting that it is a Mediterranean endemic species with a restricted distributional range.

Iphinoe daphne is typical of soft bottom habitats, from 3 to 15 meters deep. In our samples, this species was found in the “fine well sorted sand” (SFBC) biocenosis (with a sand percentage ranging from 69.7 to 90.6%) and had mean values of organic matter of 0.4%, but it was also found in deeper biocenosis, such as coastal terrigenous mud (VTC), with a silt and clay percentage ranging from 20% to 70% and an average value of organic matter of 1.2%.