Intermedichelia jesseri, Araújo-Silva, Catarina De L. & Larsen, Kim, 2012

Araújo-Silva, Catarina De L. & Larsen, Kim, 2012, Tanaidacea (Tanaidacea: Crustacea) from Brazil. IV. A new genus and two new species from the family Leptocheliidae, Zootaxa 3523, pp. 1-19 : 13-18

Intermedichelia jesseri n. sp.

( Figs. 7–9 )

Material examined. Holotype: ovigerous female (REG# MOUFPE 14.323), 3.7 mm body length. Station NE IV #131 (02°23’S 039°89’W). Type locality: Ceará State [CE], Brazil. Depth: 40 m, 20 November 2000.

Paratypes: one female with oostegites (dissected) (REG# MOUFPE 15.069); three females without oostegites (REG# MOUFPE 14.324), same locality of holotype. One female without oostegites (REG# MOUFPE 14.325); station NE IV #178 (011°27’S 037°02’W), 3 December 2000. Specimens were collected in sandy sediment, sorted from algae and sponges, depth: 71.6 m. Locality: Sergipe State [SE], Brazil.

Diagnosis. Female. Lateral projections on pereonite 3 with two distal simple setae. Antennule with several setulated setae. Maxilliped basis with two distal simple setae. Pereopod 3 with one ventrodistal spiniform seta on merus, carpus and propodus. Pereopods 4–6 basis very stout, about 1.5 times as long as wide; propodus dorsodistal seta only marginally longer than dactylus. Uropod exopod uniarticulate.

Etymology. The species is named after of the amphipod specialist and friend Prof. Jesser Fidelis de Souza Filho. The name ‘ jesseri ’ is a Latinization of his given name.

Description. Based on holotype (3.7 mm) and paratype, ovigerous female.

Body ( Fig. 7 A): dorsoventrally flattened, about 7.3 times as long as wide.

Cephalothorax: about 1.3 times as long as wide, naked, as long as two first pereonites combined. Rostrum short, but visible rounded on top. Triangular eye-lobes and visual elements present.

Pereon: about 4.6 times as long as wide, about 64% of total body length and 3.6 times as long as cephalothorax. Pereonite 1 shortest, about two times as long as wide. Pereonites 2, 5 and 6 subequal; with one mediolateral simple seta on each margin. Pereonite 3 with medial lateral projections with two distal simple setae. Pereonite 4 longest, slightly longer than wide.

Pleon: about 1.5 times as long as wide and about 25% of total body length. Pleonites subequal, with one or two simple seta on each lateral margin. Pleotelson about twice as long as wide, with one pair of simple setae on medial and posterodistal margins.

Antennule ( Fig. 9 D): of four articles (terminal article reduced), about 1.2 times as long as cephalothorax. Article 1 elongate, 1.5 times as long as following articles combined and 3.7 times as long as wide, with five ventromedial setulated setae, ventrodistal margin with one simple and three setulated setae, one dorsodistal simple seta. Article 2 as long as article 3, with one ventrodistal simple seta, dorsodistal margin with one setulated and one simple seta. Article 3 with five distal simple setae. Terminal article with three simple setae and two aesthetascs.

Antenna ( Fig. 9 E): of six articles (terminal article reduced), about 0.6 times as long as antennule. Article 1 naked. Article 2 as long as article 3, ventral margin with a row of fine simple setules, two simple setae and one strong simple seta distally, one dorsodistal spiniform seta. Article 3 with a row of fine simple setules and one distal simple seta. Article 4 as long as previous articles combined, inner margin with one medial simple seta, one setulated and two distal simple setae, outer margin with one medial simple seta, one setulated, one simple seta and three setulated setae. Article 5 about 0.5 times as long as article 4, with two distal simple setae and one setulated seta. Terminal article with four simple setae.

Mouthparts ( Fig. 7 C–G): Labrum not recovered. Mandibles ( Fig. 7 C, D) molar process broad, with serrate edges (not illustrated). Left mandible ( Fig. 7 C) incisor and lacinia mobilis with six denticles and proximal denticle crenulate. Right mandible ( Fig. 7 D) with about seven denticles. Labium ( Fig. 7 E) with two pairs of lobes, rounded on top, with several fine simple setules on distal margin. Maxillule ( Fig. 7 F) palp uniarticulate, endite with ten distal spiniform setae, with several fine simple setules on each lateral margin. Maxilla not recovered. Maxilliped ( Fig. 7 G) endite with fine simple setules, two complex setae and one simple seta on distal margin; basis about 2.2 times as long as wide, with two distal simple setae. Palp article 1 naked; article 2 with one outer distal simple seta, inner margin with a row of fine simple setules and five simple setae; article 3 as long as article 4, with seven simple setae on inner margin; article 4 with several fine simple setules and eight simple setae. Epignath not recovered.

Cheliped ( Fig. 9 C): attached via sclerite. Basis about 1.9 times as long as wide, with one dorsodistal simple seta. Merus with two ventral simple setae. Carpus about twice as long as wide and slightly longer than basis, dorsal margin with one medial and one distal simple seta, two ventrodistal simple setae. Propodus about 1.2 times as long as wide, inner distal margin with one distal simple seta, four bipinnate setae and two simple setae, outer margin with one short distal simple seta and one long simple next to dactylus insertion. Fixed finger with two ventral simple setae and three simple setae on inner margin. Dactylus and unguis naked, as long as fixed finger.

Pereopod 1 ( Fig. 8 A): coxa with one simple seta. Basis about 3.8 times as long as wide, dorsoproximal margin with one short spiniform seta, one simple seta and two setulated setae. Ischium with two ventral simple setae. Merus about 1.3 times as long as wide, naked. Carpus slightly longer than merus, with two dorsodistal simple setae, ventrodistal margin with three simple setae and one setulated seta. Propodus about 3.7 times as long as wide and 1.4 times as long as carpus, with three subdistal simple setae, ventral margin with two simple setae and one setulated seta. Dactylus and unguis combined about 27% of pereopod 1 total length, about 1.6 times as long as propodus and slightly longer that basis. Unguis slightly longer than dactylus.

Pereopod 2 ( Fig. 8 B): as pereopod 1 except basis dorsoproximal margin with one simple and one setulated seta. Ischium with one ventral simple seta. Merus with one ventrodistal simple seta. Carpus with one dorsodistal simple seta and three ventrodistal simple setae. Propodus about 2.8 times as long as wide, with two dorsodistal simple setae and three ventrodistal simple setae. Dactylus and unguis combined about 0.5 times as long as propodus, with one dorsodistal simple seta. Unguis as long as dactylus.

Pereopod 3 ( Fig. 8 C): as pereopod 2 except merus with one ventrodistal spiniform seta. Carpus with two simple setae and one spiniform seta on ventrodistal margin, one dorsodistal simple seta. Propodus dorsal margin with one medial simple seta, one long and one short spiniform seta distally, one subdistal simple seta.

Pereopod 4 ( Fig. 8 D): no visible coxa. Basis stout, naked, about 1.5 times as long as wide. Ischium with two ventral simple setae. Merus slightly longer than carpus, ventrodistal margin with fine simple setules and one spiniform seta. Carpus with one inner dorsodistal spiniform seta, two outer ventrodistal spiniform setae with medial ring of spinules. Propodus about 2.7 times as long as wide, dorsodistal margin with one setulated seta, two spiniform setae, one circumplumose spiniform seta and one marginally longer than dacytlus and unguis combined, one ventrodistal spiniform seta. Dactylus and unguis combined 0.5 times as long as propodus. Unguis 0.7 times as long dactylus, incompletely fused with dactylus.

Pereopod 5 ( Fig. 9 A): as pereopod 4 except merus each distal margin with one short spiniform seta and one spiniform seta with medial ring of spinules. Carpus each distal margin with one spiniform seta with medial ring of spinules. Propodus dorsodistal margin with three simple setae (one marginally longer than dactylus and unguis combined), one spiniform and one circumplumose spiniform seta, ventrodistal margin with one simple seta and two spiniform setae.

Pereopod 6 ( Fig. 9 B): as pereopod 5 except basis with one ventromedial simple seta. Merus with two ventrodistal spiniform setae with medial ring of spinules. Carpus with one dorsodistal simple seta. Propodus dorsodistal margin with two simple setae (one as long as dactylus and unguis combined), four spiniform setae and one bipinnate seta, one ventrodistal spiniform seta.

Pleopods ( Fig. 7 B): basal article trapezoidal, with one plumose seta. Exopod with 16 plumose setae and one proximal plumose seta. Endopod with one outer medial plumose seta and 13 inner plumose setae, distal seta with serrate apex.

Uropod ( Fig. 9 F): basal article naked. Exopod uniarticulate, about 0.7 times as long as article 1 of endopod, with two distal simple setae. Endopod of five articles; articles 1, 2 and 4 subequal; article 3 with two simple setae and one setulated seta; article 5 with five distal simple setae.

Geographical distribution. The species of the genus are endemic to the Brazilian coast. Western Mid- Atlantic: Ceará [CE] to Sergipe State [SE], Brazil.

Remarks. Intermedichelia jesseri is very similar in body-shape and mouthparts morphology to I. gracilis . However, they can be separated by the following combination of characters: 1) the lateral projections of pereonite 3 with two distal simple setae (one in I. gracilis ), 2) the article 1 of antennule with several setulated setae (absent in I. gracilis ), 3) the maxilliped basis with two distal simple setae (three in I. gracilis ), 4) the pereopod 3 with one ventrodistal spiniform seta on merus, carpus and propodus (absent in I. gracilis ), 5) the pereopods 4–6 with basis much wider (about 1.5 times as long as wide) than in I. gracilis (about 2.5 times as long as wide), 6) the pereopods 4–6 propodus dorsodistal seta only marginally longer than dactylus and unguis combined (more than twice as long as dactylus and unguis combined in I. gracilis ), 7) the uropod exopod uniarticulate (biarticulate in I. gracilis ). Also Guţu (1996: 113, fig. 37c) illustrates- but do not mention- a strange maxilliped palp configuration where both articles 1 and 2 are attached to the basis. However, we consider this feature an artefact.

During the same collection program, we found specimens of I. gracilis which confirm the differences between these two species. The only character used by Bird and Larsen (2009: 148[94]) to remove Intermedichelia from the Leptocheliidae was that the propodus of pereopods 4–5 carried modified dorsodistal setae. Since this feature is now shown to vary within the genus, we here transfer Intermedichelia to the family Leptocheliidae .

Figures

FIGURE 7. Intermedichelia jesseri n. sp., female, holotype. (A) Dorsal view. Paratype, female: (B) pleopod; (C) left mandible; (D) right mandible; (E) labium; (F) maxillule; (G) maxilliped. (A) Scale bar = 1 mm; (B) scale bar = 0.2 mm and (C – G) scale bar = 0.1 mm.

FIGURE 8. Intermedichelia jesseri n. sp., female, paratype. (A) Pereopod 1; (B) pereopod 2; (C) pereopod 3; (D) pereopod 4. (A – D) Scale bars = 0.2 mm.

FIGURE 9. Intermedichelia jesseri n. sp., female, paratype. (A) Pereopod 5; (B) pereopod 6; (C) cheliped; (D) antennule; (E) antenna; (F) uropod. (A – E) Scale bars = 0.2 mm and (F) scale bar = 0.1 mm.