Dolicholana ivanyae, Paiva & Souza-Filho, 2023

Paiva, Ricardo J. C. & Souza-Filho, Jesser F., 2023, Three new species of the family Cirolanidae Dana, 1852 (Isopoda, Cymothoida) from the shallow Brazilian bathyal, Zootaxa 5319 (1), pp. 1-26 : 3-9

Dolicholana ivanyae spec. nov.

( Figs 1–6 )

Material examined. Holotype: male, 15 mm, (dissected and drawn, 8 slides), Revizee Sul, station # 6743, Box Corer, 23°55’40”S, 42°47’60”W, 508 m, 15 February 1998, MNRJ 20208 .

Paratypes: 1 manca (8 mm, drawn, pereopod 7 present not full developed), Santos Basin, S „o Paulo , Brazil, Station BS-N-07, 137G266, 26º03’26.15”S, 45º42’28.88”W, 24 May 2002, 440 m, MZUSP 25641 . 1 manca (7 mm, lacking pereopod 7), Revizee Central , station # 6752, Box Corer, 15°49’58.8”S 38°35’27.6”W, 250 m, 16 February 1998, MNRJ 20207 .

Type locality. Brazil, 23°55’40”S, 42°47’60”W.

Etymology. Named after Ivanya Vieira da Silva Paiva, wife of the first author.

Diagnosis. Head interocular furrow present, submarginal furrow absent, dorsal furrow complete. Eyes separated by about 50% head width, strongly pigmented. Frontal lamina 1.5 times as long as wide, linguiform, anterior margin rounded, visible in dorsal view and reaching antenna 1 article 2. Pereopod 7 different from pereopod 6 in shape and ornamentation, densely setose, basis, ischium and merus anterior and posterior margins with very long plumose setae. Pleonite 1 not visible in dorsal view. Pleonite 3 posteroventral angle subacute and entire. Pleopods 3–5 endopod lacking marginal setae. Pleopod 5 exopod with complete suture. Pleotelson longer than wide, apex broadly rounded, distal margin with plumose setae, lacking RS.

Description of male holotype. Body 3.1 times as long as greatest width, dorsal surface smooth, widest at pereonite 5, lateral margins slightly convex. Rostral point absent, frontal margin truncate. Eyes separated by about 50% head width, eye colour black. Pereonite 1 and coxae 2–3 each with posteroventral angle rounded; coxae 2–7 with entire oblique carina; pereonites 5–7 posterior margins smooth. Pleon with pleonite 1 almost concealed by pereonite 7; pleonites 2–5 posterior margin smooth; pleonite 2 posterolateral angles forming subacute point, not posteriorly produced; pleonite 3 posterolateral margins acute and not extending to pleonite 5 posterior margin; pleonite 4 posterolateral margin rounded extended beyond pleonite 5 posterior margin; pleonite 5 with posterolateral angles overlapped by pleonite 4 lateral margins. Pleotelson shorter than anterior width (0.87 times), without longitudinal carina, without dense patch of setae; lateral margins convex, smooth; posterior margin broadly rounded, with plumose setae.

Antenna 1 peduncle articles 1 and 2 distinct and articulated; article 2 0.80 times as long as article 1; article 3 and 4 0.60 times as long as articles 1 and 2 length combined; article 3 almost as long as wide; flagellum moderately widened medially, with 12 articles, extending beyond to eye posterior margin. Antenna 2 peduncle article 4 1.5 times as long as wide, almost as long as article 3, with 3 short simple setae (distal); article 5 1.2 times as long as article 4, 2.4 times as long as wide, anterodistal angle with cluster of 3 short simple seta; flagellum with 22 articles, extending to pereonite 2.

Frontal lamina long and linguiform, ventral surface entirely flat, 1.5 times longer than greatest width, lateral margins slightly convex, anterior margin rounded, visible in dorsal and reaching antenna 1 article 2. Mandible molar process anterior margin with 20 flat teeth; with proximal cluster of long simple setae; right mandible spine row composed of 8 spines; palp article 2 with 20 distolateral setae, article 3 with 13 slender setae. Maxillula mesial lobe with 3 large CPS RS and 1 short large CPS RS; lateral lobe with 11 RS. Maxilla lateral lobe with 5 long simple setae; middle lobe with 11 long simple setae; mesial lobe with 11 distal pappose setae. Maxilliped palp article 1 mesial margin without setae, lateral margin distally with 5 long CPS; article 2 mesial margin with 11 slender setae, lateral margin with 2 long and plumose setae; article 3 mesial margin with 14 slender setae, lateral margin with 6 long CPS and 2 slender setae; article 4 mesial margin with 14 slender setae and 4 pappose setae, lateral margin with 3 long CPS; article 5 distal margin to mesial margin with 15 slender setae and 6 pappose setae, lateral margin with 2 long and plumose setae; endite with 5 long CPS and 2 coupling setae.

Pereopod 1 basis 2 times as long as greatest width, superior margin with 8 short plumose setae, superior distal angle with lacking cluster of setae, inferior margin with 6 long and slender setae, inferior distal angle with a cluster of 8 slender setae; ischium 0.8 times as long as basis, inferior margin with 9 simple setae and 2 RS, inferior distal margin without setae, superior margin with a middle and long CPS, superior distal margin produced over merus and with a cluster of long and slender setae, mesial margin with a cluster of long and slender setae; merus inferior margin with a row of 13 simple setae, superior distal angle produced and reaching 2/3 of carpus, superior margin with a row simple and RS; carpus inferior margin lacking setae, inferior distal angle with 2 RS; propodus 2.5 times as long as wide, inferior margin with 6 simple setae and 4 RS, inferior distal margin with 1 RS and 6 simple setae, superior distal margin with 4 short setae; dactylus 0.7 times as long as propodus. Pereopod 2 ischium inferior margin with 12 long simple setae, inferior distal margin without setae, superior distal margin produced over merus and with a cluster of long and slender setae, mesial margin with a cluster of long and slender setae; merus inferior margin with 2 stout RS and 6 acute RS, set as single row, inferior distal margin with 2 RS, superior distal angle produced and reaching 2/3 of carpus, superior margin with a row of both long and simple and 7 stout RS, mesial margin with a row of 4 stout RS and 13 simple and long setae; carpus inferior margin with 3 stout RS, inferior distal margin with 3 long acute RS and 4 simple seta; propodus 2.2 as long as wide, inferior margin with 2 long RS and 4 simple setae, inferior distal margin with 1 short RS and 3 simple setae; dactylus 0.8 times as long as propodus. Pereopod 3 similar to pereopod 2. Pereopods 4–6 similar to each other. Pereopod 7 both inferior and superior margins densely setose (plumose setae); basis slightly ovate, 2.2 times as long as greatest width; ischium 0.6 times as long as basis, 1.7 times as long as wide, widened distally; merus 0.5 times as long as ischium, 1.8 times as long as wide; carpus 0.5 times as long as ischium, 2.6 times as long as wide; propodus 0.5 times as long as ischium, 4.6 times as long as wide, inferior margin with 1 RS; dactylus 0.7 times as long as propodus. Penes distinct flat rounded lobes, separated by 15% of sternal width.

Pleopod 1 exopod 1.3 times as long as wide, lateral margin slightly convex, distally broadly rounded with strongly oblique medial margin, mesial margin strongly convex, with PMS from distal two-third, with ~90 PMS; endopod 1.4 times as long as wide, distally narrowly rounded, with PMS from distal one-third, mesial margin with PMS from distal one-third, endopod with ~20 PMS; peduncle 0.45 times as wide as long, mesial margin with 7 coupling setae. Pleopod 2 exopod with ~90 PMS, endopod with ~21 PMS; appendix masculina inserted medially, with parallel margins, as long as endopod, distally subacute. Pleopod 3 exopod with ~100 PMS, endopod without PMS. Pleopod 4 exopod with ~75 PMS, endopod without PMS. Pleopod 5 exopod biarticulate, with ~55 PMS from distal two-third, endopod without PMS. Pleopods 2–5 endopod distal margin subacute.

Uropod peduncle ventrolateral margin with 1 long RS, 1 short RS and 2 PMS, lateral margin with medial 4 short acute RS and 2 PMS, posterior lobe 0.80 times as long as endopod; rami extending beyond pleotelson, lateral, distal and mesial margin lined with long PMS. Endopod apically truncate; lateral margin straight, without prominent excision; mesial margin straight. Exopod not extending to end of endopod, 3.3 times as long as greatest width, apically rounded; lateral and mesial margin straight.

Distribution. Bahia, Rio de Janeiro and S„o Paulo ( Brazil), 250–508 m depth ( Fig. 7 ).

Variation. Two smaller individuals, mancae with 7 mm (MNRJ 20207) and juvenile with 8 mm (MZUSP 25641) have pleonite 1 not covered by pereonite 7, while in adult male holotype (15 mm, MNRJ 20208) the pereonite 7 hidden almost completely the pleonite 1. This character was not observed in other species of Dolicholana , which may be due to differing ontogenetic development of the species.

Remarks. Dolicholana ivanyae spec. nov. is similar to D. brucei , recently described from Brazil (the Potiguar Basin off Rio Grande do Norte), and D. elongata , from the Pacific Ocean, in having a long frontal lamina that is visible in the dorsal view between the antennae, and the broadly rounded distal margin of the pleotelson. Dolicholana ivanyae spec. nov. can nevertheless be differentiated from D. brucei due to the frontal lamina surpassing article 2 of the peduncle of antenna 1 (vs. slightly surpassing peduncle 1) and visible dorsally between the antennae (vs. not visible dorsally), eyes separated by about 50% of the width of the head (vs. 18%), head with truncated anterior margin (vs. rounded), dorsal groove present (vs. absent), pereopod 7, densely setose, anterior and posterior margins of the basi-ischium and merus with very long plumose setae (vs. short plumose setae), uniarticulate endopods of pleopods 3 and 4 (vs. biarticulate), and distal margin pleotelson with no RS (vs. distal margin with two RS).

Dolicholana ivanyae spec. nov. differs from D. elongata based on the following combination of characters: head with truncated (vs. slightly concave) anterior margin, dorsal groove present (vs. absent), frontal lamina very elongated surpassing article 2 of the peduncle of antenna 1 (vs. slightly surpassing article 1), pereopod 7 basis anterior and posterior margins densely setose with very long setae (vs. short setae), endopods of pleopods 3 and 4 uniarticulated (vs. biarticulate), pleotelson with distal margin lacking RS (vs. two RS), epimera 3 and 4 with a subacute (vs. rounded) posteroventral angle. A comparison of selected morphological parameters for all the species of the genus Dolicholana , including the new species, is provided in Table 1 .

Figures

FIGURE 1. Dolicholana ivanyae spec. nov., Holotype, male, 15 mm (MNRJ 20208). A = habitus dorsal view; B = habitus lateral view. Paratype, male, 8 mm (MZUSP 25641). C = habitus dorsal view; D = habitus lateral view. Scale bars = 1 mm.

FIGURE 2. Dolicholana ivanyae spec. nov., Holotype, male, 15 mm (MNRJ 20208).A = Head oblique view; B = Head ventral view; C = Head dorsal view; D = Head = frontal view; E = Pleontelson. Scale bars = 0.5 mm.

FIGURE 3. Dolicholana ivanyae spec. nov., Holotype, male, 15 mm (MNRJ 20208). A–B = Maxilla 1–2; C= Antenna 1; D = Antenna 2; E = Maxilliped; F = Mandible. Scale bars = 0.5 mm.

FIGURE 4. Dolicholana ivanyae spec. nov., Holotype, male, 15 mm (MNRJ 20208). A–D = Pereopods 1–4. Scale bars = 0.5 mm.

FIGURE 5. Dolicholana ivanyae spec. nov., Holotype, male, 15 mm (MNRJ 20208). A–C = Pereopods 5–7; D = Pereonites 6–7; pleonites 1–5 (Paratype, Male, 8 mm, MZUSP 25641). Scale bars = 0.5 mm.

FIGURE 6. Dolicholana ivanyae spec. nov., Holotype, male, 15 mm (MNRJ 20208). A–E = Pleopods 1–5; F = Uropod. Scale bars = 0.5 mm.

FIGURE 7. Map showing distribution of the species: D. brucei (= circle), Dolicholana ivanyae spec. nov. (= square), Natatolana hadassae spec. nov. (= star) and Politolana cleoniceae spec. nov.(= pentagon).