Cirolana westbyi Jennings & Bojko, 2021

Jennings, Lucas A., Bojko, Jamie, Rotjan, Randi D. & Behringer, Donald C., 2021, Cirolana westbyi, (Isopoda: Cirolanidae) a new species in the ‘ Cirolana parva-group’ from the Turneffe Atoll, Belize, Journal of Natural History 54 (31 - 32), pp. 2053-2069 : 2056-2063

Family: Cirolanidae Dana, 1852

Genus: Cirolana Leach, 1818

Cirolana westbyi Jennings & Bojko n. sp.

( Figs 1–3 )

Material examined Holotype. Adult male ( FMNH Arthropoda #51013), 10.000 mm, Westby fishing camp on Turneffe Atoll, Belize (17°13 ʹ.023”N, 87°29 ʹ 40.63”W), collected from a baited spiny lobster trap . Paratypes: 28 females (16 measured, 5.1–9.1 mm, average 6.327 mm; 12 unmeasured), 4 males (3 measured, 4.4–10.0 mm, average

6.9 mm; 1 unmeasured). Holotype male and an unmeasured female deposited at the Florida Museum of Natural History , Gainesville, Florida ( USA), under: FMNH Arthropoda #51013.

Description

Body 3 times as long as greatest width; widest at pereonite 5 tapering slightly to the posterior end ( Figure 1 (a)). Eyes black, separated by 67% width of head, slightly inserted into pereonite 1 ( Figure 1 (e)). Cephalon 30% wider than medial length, bearing a small rostral process between the antennal bases. Cephalic furrow between the eyes present. Pereonites 1–7 with lateral margins rounded ( Figure 1 (f)). Coxae 4–7 posteroventral margins acute. Pereonite 7 overlapping pleonite 1, only lateral sides of pleonite 1 visible from the dorsal surface; pleonites 2–3 with posterior margins acute and extending to pleonite 4 ( Figure 1 (d)). Pleotelson ( Figure 4 (a)) 0.98 times longer than wide, lateral margins smooth and convex, posterior margin with 8 spines each set within a notch, lacking longitudinal carina.

Antennula ( Figure 1 (b)) peduncle articles 1 and 2 entirely fused, 1.6 times longer than wide; articles 3 and 4 fused, 1.2 times as long as the combined length of articles 1 and 2; article 4 2.6 times longer than wide. Antennula flagellum with 11 articles extending to anterior of pereonite 1. Antenna ( Figure 1 (c)) peduncle articles 1–3 short; article 4 2.4 times longer than article 3, 2.1 times longer than wide; article 5 1.0 times as long as article 4, 2.4 times longer than wide. Antennal flagellum with 31 articles extending to middle of pereonite 4.

Frontal lamina ( Figure 1 (g)) pentagonal, 1.6 times as long as posterior width, 1.4 times as long as greatest width, lateral margins parallel. Apex of lamina slightly covered by the rostral process.

Mandible ( Figure 2 (a,c)) molar process anterior margin with 22 flat teeth; with proximal cluster of short SS; right mandible spine row composed of 8 spines; palp article 2 with distolateral setae; palp article 3 lateral margin with 17 RS, distal margin with 4 biserrate setae. Maxillule ( Figure 2 (d)) mesial lobe with 3 large CPS; lateral lobe with 10 RS and 7 slender setae. Maxilla ( Figure 2 (b)) lateral lobe with 5 long SS, middle lobe with 11 long SS, mesial lobe with 11 long SS and 3 plumose setae. Maxilliped palp ( Figure 2 (e)) article 2 mesial margin with a cluster of 3 SS, lateral margin with a single SS; article 3 mesial margin with 10 SS and distal margin with 5 SS; article 4 mesial margin with 11 SS, distal margin 4 SS; article 5 mesial margin with 13 SS, distal margin with SS; endite ( Figure 2 (f)) with 4 long CPS.

Pereopod 1 ( Figure 3 (a,b)) basis 2.1 times longer as the greatest width, inferior distal angle with 2 RS and 1 SS; ischium 0.8 times as long as basis, inferior distal angle with a single RS, superior distal angle with a single RS; merus inferior margin with 2 RS and 5 molariform setae set in a rows of 3 and 2, superior distal angle with a single RS; carpus, inferior distal angle bearing a single SS; propodus 2.8 times longer than wide, inferior distal angle with 2 RS and a single stout bluntly rounded RS; dactylus ( Figure 3 (d)) 0.5 times as long as propodus. Pereopod 2 ( Figure 3 (c)) basis 2.8 times longer than greatest width, inferior distal angle with 2 SS; ischium superior distal angle with 2 large RS, inferior distal angle with 2 RS and a single stout bluntly rounded RS; merus inferior edge with 5 stout bluntly rounded RS and 3 SS, inferior distal angle with 1 RS and 1 stout bluntly rounded RS, superior distal angle with 2 short RS and 2 long RS and 2 SS; carpus inferior distal angle with 3 RS (1 biserrate); propodus 2.6 times longer than wide, inferior edge with 2 RS, inferior distal angle with a single stout bluntly rounded RS; dactylus 0.5 times as long as propodus. Pereopod 3 similar to pereopod 2. Pereopod 4 ( Figure 3 (e)) basis 2.0 times longer greatest width with inferior distal angle bearing a SS seta; ischium inferior edge with 2 clusters of SS, inferior distal angle with a cluster of SS, superior distal angle with 2 long SS and 2 short SS; merus inferior edge with a cluster of SS, inferior distal angle with a cluster of long and short SS, superior distal angle with a cluster of long SS; carpus inferior edge with a cluster of SS, inferior distal angle with a cluster of long SS, superior distal angle with cluster of long SS; propodus inferior edge with 2 clusters of short SS, inferior distal angle with a cluster of SS. Pereopod 7 ( Figure 3 (f)) basis 2.1 times longer than greatest width, superior margin weakly convex, inferior distal angle with a single SS; ischium 0.7 times as long as basis, inferior margin with 6 small RS set in 3 groups of 2, inferior distal angle with 3 small RS, superior distal angle with 4 RS; merus 0.6 times as long as ischium, 1.7 times longer than greatest width, inferior margin with 2 RS, superior distal angle with 10 RS (5 biserrate), inferior distal angle with 5 RS; carpus 0.7 times as long as ischium, 2.2 times as long as the greatest width, inferior margin with 4 small RS set in 2 groups of 2, superior distal angle with 10 RS (5 biserrate), inferior distal angle with 12 RS (5 biserrate); propodus 0.8 times as long as ischium, 4.3 times as long as the greatest width, inferior margin with 4 RS set in 2 groups of 2, superior distal angle with 1 RS and 2 SS, inferior distal angle with 2 RS; dactylus 0.4 times as long as propodus.

Penes ( Figure 5 (f)) low tubercles, mutually adjacent.

Pleopod 1 ( Figure 5 (a)) exopod 1.7 times longer than wide, lateral margin convex, mesial margin strongly convex, distal margin convex with 31 PMS from distal one third; endopod 1.7 times longer than wide,slightly shorter than exopod,lateral and mesial margins parallel,distal margin convex with 14 PMS; peduncle 1.7 times long as wide, mesial margin with 5 coupling hooks. Pleopod 2 ( Figure 5 (b)) exopod 1.7 times longer than wide, lateral and distal margins convex, distal margin strongly convex, lateral to distal end with 40 PMS; endopod 1.7 times longer than wide, lateral and mesial margins parallel, mesial margin with appendix masculina in male ( Figure 5 (c)), appendix masculina with parallel margins, distal margin convex with 15 PMS; Pleopod 4 ( Figure 5 (d)) exopod 1.5 times longer than wide, lateral margin convex with an indent near the distal end, mesial margin convex with an indent near the distal end, distal margin convex, lateral to distal margins with 50 PMS; endopod 1.4 times longer than wide, lateral margin slightly convex, mesial margin slightly concave, distal margin with 14 PMS. Pleopod 5 ( Figure 5 (e)) exopod 1.2 times longer than wide, covering endopod, distal and mesial margins convex with indentation near the distal end, distal margin convex; endopod 1.3 times longer than wide, lateral margin slightly convex, mesial margin slightly concave, distal margin slightly concave.

Uropod ( Figure 4 ) exopod tapered, rami slightly shorter than endopod, tip bifid, mesial margin with 3 RS, lateral margin with 6 RS (see variation); endopod wide, lateral side convex, mesial side straight, rami extending to the pleotelson apex, tip bifid, mesial margin with 5 RS, lateral margin with 3 RS.

Female Of similar appearance to male, lacking primary sexual characters.

Variation

Nineteen specimens were measured for the uropod and pleotelson RS. Uropod exopod RS mesial margin with 3–4 (3 = 95%, 4 = 5%), lateral margin with 6–8 (6 = 33%, 7 = 33%, 8 = 33%); uropod endopod RS mesial margin with 3–6 (3 = 5%, 5 = 84%, 6 = 11%), lateral margin with 2–4 (2 = 5%, 3 = 90%, 4 = 5%). Pleotelson normally with 8 RS (4 + 4 arrangement; 8 = 95%) however, one female had 5 RS.

Colour

Black chromatophores cover the dorsal surface of adult animals when live. Some individuals bear black chromatophores on the pereopods. Several individuals have large dark patches of chromatophores on the dorsal surface ( Figure 6 ).

Etymology

The species name is derived from the surname of the fisherman, Mr. Leopold Westby, who first approached the team with specimens.

Remarks

Cirolana westbyi n sp. is characterised by the uropodal endopod being convex on the mesial margin and straight on the lateral margin, the shape of the penial openings, by the antennula having 11 flagellar articles, the antenna having 31 articles and the adult size ranging from 8–10 mm.

Of the species known from this region, Cirolana westbyi n. sp. is similar to C. parva , C. albida and C. albidoida . Cirolana westbyi n. sp. can be separated by the straight mesial margin to the uropodal endopod (both uropodal margins convex in C. parva and C. albida ).; in C. albidoida , the uropodal endopod is tapered ( Figure 7 ). Another character that can be used to separate these species is the number of antennula and antenna flagellar articles. In C. westbyi n sp. the number of antennule and antenna flagella articles is 11 and 31 respectively. Both C. parva and C. albida have 9 antennula flagella articles while C. albidoida has 10. When considering antenna articles, C. parva has 26, C. albida has 23 and C. albidoida has 19. Cirolana westbyi n. sp. can further be separated based on adult size. Cirolana westbyi n. sp. ranges in size from 8–10 mm while C. parva has a size range of 5–7 mm. Cirolana albidoida has a similar adult size as C. westbyi n. sp. but the two can be distinguished by the uropodal endopod characters as stated above. The original species description for C. albida contains no information on adult size.

Figures

Figure 1. Cirolana westbyi n sp. male (a) dorsal view; (b) antennula; (c) antenna peduncle; (d) pleon; (e) head; (f)lateral view; (g)frontal lamina.

Figure 2. Cirolana westbyi n sp. male (a) right mandible; (b) right maxilla; (c) distal part of right mandible; (d) right maxillule; (e) right maxilliped; (f)mesial part of right maxilliped showing endite.

Figure 3. Cirolana westbyi n sp. male (a) pereopod 1; (b) mesial view of pereopod 1; (c) pereopod 2; (d) mesial view of dactylus of pereopod 1; (e) pereopod 4; (f)pereopod 7.

Figure 4. Cirolana westbyi n sp. male (a) pleotelson; (b) uropod; (c) pleotelson apex; (d) uropod endopod apex; (e) uropod exopod apex.

Figure 5. Cirolana westbyi n sp. male (a) pleopod 1; (b) pleopod 2; (c) appendix masculina; (d) pleopod 4; (e) pleopod 5; (f) penial openings.

Figure 6. Cirolana westbyi specimen showing large patches of chromatophores n. sp. collected on site in 2018 and calmed using a weak alcohol solution for stacked imaging. Photo taken by John Majoris.

Figure 7. Differences in uropodal shape of some of the species of Cirolana found in the Gulf of Mexico. (a) Cirolana albidoida, (b) C. albida, (c) C. parva, (d) C. westbyi n. sp. Position of the arrowhead indicates the location of the shape difference among the different species.Uropod sketches for C. albidoida and C. albida were developed from Kensley and Schotte (1987). Uropod sketch for C. parva was developed from Bruce and Bowman (1982).