Ianiropsis cf. serricaudis Gurjanova, 1936

Morales-Nunez, Andres G & Chigbu, Paulinus, 2018, First record of Ianiropsiscf. serricaudis in Maryland Coastal Bays, USA (Crustacea, Peracarida, Janiridae), ZooKeys 747, pp. 115-139 : 117-130

Ianiropsis cf. serricaudis Gurjanova, 1936 Figures 2, 5, 6, 7, 8, 9, 10, 11, 12, 13D

Material examined.

13 ♂♂ (three USMN: 1480972, 1480973, and 1480974), one ovigerous ♀, two ♀♀ carrying juveniles (one USNM 1480975), and 13 ♀♀ with oostegites (two USNM: 1480976 and 1480977), station-8 (38°16.825'N − 75°08.032'W), Sinepuxent Bay, USA, depth 3.1 m, October 25-2012, collected by A.G. Morales-Núñez.

Description.

Based on adult terminal ♂ of Ianiropsis cf. serricaudis from Maryland Coastal Bays. Body (Fig. 5A). TL 3.0 mm, about 3.1 times as long as wide, pigmentation in preservative scattered brown pigment.

Head (Fig. 5A). ~0.15 TL, 1.7 width, anterior margin with a light median convexity, posterior margin linear, each lateral margin with small simple setae of various lengths, longer than pereonite 1. Eyes dorsal, set back from lateral margin, pigmented with more than 15 well-developed ommatidia.

Pereon (Fig. 5A). ~0.6 TL, all pereonites wider than long, pereonites 1-3 sub-equal in length, pereonites 4 and 5 shorter than pereonites 1-3 and 5-6, both lateral margins of each pereonite with small simple setae of various lengths.

Pleotelson (Fig. 5 A–B). ~0.25 TL, ovate, with three to four denticles on each lateral margin (Fig. 5 A–B).

Antennule (Figs 5A, 6A). ~0.25 TL, tip reaching 0.73 of length of antennal article 5, with 13-14 articles. Article 1 widest, 1.1 times as long as wide, inner margin with a sub-proximal small simple seta and two (one simple and one sensory) distal setae; outer margin with three (two short) distal setae. Article 2, 1.3 times as long as wide, distal margin with row of seven simple setae of unequal lengths; outer mid-margin with sensory seta. Article 3, 1.2 times as long as wide, asetose. Flagellum with ten articles; articles 8, 10 and 13 with one aesthetasc. Article 13 minute, with three distal simple setae of various lengths.

Antenna (Figs 5A, 6B). As long as body, articles 1-6 about ½ of TL. Articles 1 and 2, wider than long, with simple seta on distal outer margin. Article 3 sub-quadrate, with small seta near to the insertion of the antennal scale. Article 4, wider than long, with two simple setae on inner distal margin. Article 5, twice as long as combined lengths of articles 1-4. Article 6, slightly shorter than article-5. Flagellum with 39-45 sub-equal articles. Antennal scale longer than article 4, with five simple setae on distal margin of varying lengths.

Mouthparts. Upper lip (Fig. 7A) broad, with fine apical setae.

Mandibles (Fig. 7 B–E). Molar process well developed with two denticulate setae (Fig. 7B and 7E, respectively); left mandible with strong incisor bearing five teeth (Fig. 7C), lacinia mobilis with five teeth and two rows of simple setae in the middle area (Fig. 7B, D); setal row with five denticulate setae (Fig. 7B); right mandible with incisor bearing five teeth, setal row with eight denticulate setae and two bifid setae (Fig. 7E). Palp article 1, 3.5 times as long as wide, with small simple seta on mid-margin and two (one longer and one small) simple setae on distal margin; article 2 longest, 2.9 times as long as wide, with three (two long and one short) denticulate setae on sub-distal lateral margin, with small simple seta on distal margin; article 3, 3.9 times as long as wide, with row of ± 25 denticulate setae along the lateral margin (Fig. 7E).

Lower lip (Fig. 7F). Two pairs of lobes with inner margins setulate.

Maxillule (Fig. 7 G–I). Inner lobe with four setulate distal setae, outer and distal margin with simple setae. Outer lobe with 12-13 robust denticulate distal setae (Fig. 7 H–I), with one simple seta on mid sub-distal margin, both margins finely setose (Fig. 7G).

Maxilla (Fig. 7 J–M). Inner lobe with seven denticulate setae (Fig. 7K), both margins finely setose. Outer and middle lobes having one “comb-like” seta (Fig. 7L) and three finely setulate setae (Fig. 7M), both margins finely setose.

Maxilliped (Fig. 8 A–G). Basis, 1.2 times wider than long. Endite, 2.0 times as long as wide, outer margin with 11-12 simple setae (Fig. 8B); inner proximal margin with two coupling hooks (Fig. 8B, F–G), sub-distal inner margin with one setulate seta and ~seven simple setae, sub-distal margin with seven (six on dorsal view (Fig. 8B) and one on ventral view (Fig. 8G), respectively) fan setae (Fig. 8C), distal margin with 12 (seven (Fig. 8B) and five (Fig. 8G), respectively) setulate setae (Fig. 8D), inner distal margin with three simple setae (Fig. 8E). Palp 7.4 times longer than basis (Fig. 8A): article 1, wider than long; article 2, wider than long, 3.4 times as long as article-1, inner distal margin with two clusters of simple setae of varying lengths; article 3, longer than wide, 1.7 times as long as wide, slightly longer than twice of article 2; mid-proximal inner margin greatest wide, with a row of simple setae of varying lengths; article 4 longest, 5.6 times as long as wide, with row of 12-13 simple setae on inner distal margin; article 5 sub-equal length of that of article 3, 9.5 times as long as wide, with a row of 10-11 simple setae on inner margin.

Pereopod I (Fig. 9 A–B). Extremely longer, 1.2 times longer than TL, basis to propodus longer than other six pereopods. Basis elongate, 8.3 times as long as wide; with eight small simple setae along dorsal margin; with one simple seta and 13 robust setae along ventral margin. Ischium elongate, 5.6 times as long as wide; with 11 simple setae along dorsal margin; with one simple seta on disto-medial margin; with six simple small setae along ventral margin. Merus elongate, 2.7 times as long as wide, widest distally; with five simple setae including two small setae along dorsal margin, disto-dorsal lobe with three distal setae; with simple seta on disto-lateral margin; with six simple setae of varying lengths on ventral margin. Carpus elongate, 4.6 times as long as wide; with eight (one small) simple setae along dorsal margin and three small disto-dorsal simple setae; with 18 simple setae and three robust setae along ventral margin. Propodus elongate, 8.0 times as long as wide; with 11 (two small) simple setae along dorsal margin and cluster of four simple setae on sub-distal dorsal margin; with four simple setae on lateral margin; with 12 simple setae along ventral margin, with five simple setae of varying lengths and one robust seta on disto-ventral margin (Fig. 9B); articular plate absent. Dactylus with two distal claws, with three simple setae on disto-medial margin between the claws, with four simple setae on disto-dorsal margin (Fig. 9B).

Pereopod II (Fig. 9 C–H). Basis, 2.4 times as long as wide; with six simple setae of varying lengths (Fig. 9D), and one sensory seta (Fig. 9E); with three small simple setae along ventral margin. Ischium, 2.6 times as long as wide; with eight simple setae along dorsal margin; with one small simple seta on distal lateral margin; with five simple setae along ventral margin. Merus, 2.0 times as long as wide, widest distally; with two simple setae along dorsal margin, disto-dorsal lobe with three robust setae (Fig. 9F); with simple setae on disto-lateral margin; with five (three distally) simple setae on ventral margin. Carpus, 3.2 times as long as wide; with seven simple setae along dorsal margin and a cluster of one sensory and six simple setae on disto-dorsal margin; with two robust setae (Fig. 9G) and ten simple setae of varying lengths along ventral margin. Propodus, 5.3 times as long as wide, with six simple setae of varying lengths and one robust seta along dorsal margin and one sensory seta and eight simple setae of varying lengths on disto-dorsal margin (Fig. 9C); with six robust setae and five simple setae along ventral margin; articular plate present on disto-lateral margin. Dactylus with three (one mid-lateral and two distal) claws, with two simple setae on distal lateral margin between the claws, with four simple setae on disto-dorsal margin (Fig. 9H).

Pereopods III–VII (Figs 9 I–J; 10 A–H, respectively). Pereopod III (Fig. 9 I–J): 0.54 times as long as pereopod I. Pereopod IV (Fig. 10 A–B): 0.46 times as long as pereopod I. Pereopod V (Fig. 10 C–D): Shortest, 0.39 times as long as pereopod I. Pereopod VI (Fig. 10 E–F): 0.45 times as long as pereopod I. Pereopod VII (Fig. 10 G–H): 0.49 times as long as pereopod I.

Pleopod I (Fig. 11A). 8.3 times as long as wide, lateral apex pointed and directed obliquely backward, distal margin with 13-15 simple setae of unequal lengths, sub-distal outer margin with 6-7 simple setae.

Pleopod II (Fig. 11B). Protopod, 1.8 times as long as wide, robust, long-oval asetose, distal margin setae absent. Endopod, stylet bi-articulated, distal tip narrow, curved inwards; exopod distal margin convex, asetose.

Pleopod III (Fig. 11C). Endopod, 2.0 times as long as wide, distal margin rounded, inner margin setulate with plumose seta distally, outer distal margin with two plumose setae; exopod 1.2 times as long as endopod, bi-articulated, articulation between two articles oblique, article 2 distal margin broadly rounded, with simple seta.

Pleopod IV (Fig. 11D). Endopod, 1.7 times as long as wide, asetose; exopod 2.4 times as long as wide, reduced, 0.27 times as long as endopod, half as long as endopod, with outer margin setulate.

Uropod (Figs 5A, 11E). 1.1 times as long as pleotelson, slightly longer than pleotelson. Protopod 1.8 times as long as wide, 1.2 times as long as exopod and slightly shorter than endopod, with six spiniform and three simple setae along the inner margin, with two simple setae on distal margin, with five simple setae along outer margin. Endopod, 5.7 times as long as wide, longer than exopod, with several plumose, spiniform and simple setae along both margins, distal margin with 13 simple setae of varying lengths. Exopod, 5.5 times as long as wide, with spiniform and simple setae along both margins, distal margin with 13 simple setae of varying lengths.

Females with oostegites.

Smaller than males, mean TL 1.98 mm; TL ranges from 0.95 to 2.52 mm (Table 2). Antennule with 7-12 articles (Table 2). Antenna generally shorter than TL (Table 2); lengths of antennal articles 5-6 combined, shorter than half TL (Table 2).

Maxilliped (Fig. 12A). Maxillipedal palps cannot be observed on dorsal view, not passing well beyond the basal articles of the antenna. Basis, as long as wide. Endite, 2.0 times as long as wide, outer margin with 7-8 simple setae; inner proximal margin with two coupling hooks, sub-distal margin with seven (six on dorsal view and one on ventral view (not shown), respectively) fan setae (Fig. 8C), distal margin with 12 (seven and five (not shown), respectively) setulate setae (Fig. 8D), inner distal margin with two simple setae. Palp 2,4 times longer than basis: article 1, wider than long; article 2, wider than long, 1.3 times as long as article 1, inner distal margin with 7-8 simple setae of varying lengths; article 3, wider than long, 1.8 times as wide as long, slightly shorter than twice of article 2; inner distal margin with a row of 14-15 simple setae of varying lengths, outer margin with three (one on middle and two on distal) simple setae; article 4, 3.3 times as long as wide, with row of 6-7 simple setae on inner distal margin; article 5, slightly shorter than twice of article 4, 2.3 times as long as wide, with a row of 7-8 simple setae on inner margin.

Pereopod I (Fig. 12 B–C). Shorter than male pereopod I, 0.48 times shorter than TL, Basis 2.0 times as long as wide; with six small simple setae along dorsal margin; with two simple seta on proximal-medial margin, and one robust and five simple setae along ventral margin. Ischium, 1.8 times as long as wide; with four simple setae along dorsal margin; with one simple seta on disto-medial margin; with two simple small setae along ventral margin. Merus, 1.5 times as long as wide, widest distally; disto-dorsal lobe with one simple and three robust distal setae, with two small setae along dorsal margin; with simple seta on disto-lateral margin; with four simple setae of varying lengths on ventral margin. Carpus, 3.4 times as long as wide; with five (three small) simple setae along dorsal margin and four disto-dorsal simple setae of unequal lengths; with simple seta on disto-lateral margin, with six simple setae and six robust setae along ventral margin. Propodus, 4.9 times as long as wide; with four simple setae along dorsal margin and cluster of four simple setae of varying lengths on distal dorsal margin (Fig. 12 B–C); with simple seta on sub-distal lateral margin, with three (one sub-distal and two distal) simple setae and five robust setae along ventral margin, articular plate absent. Dactylus with two distal claws, with two simple setae on disto-medial margin between the claws, with two simple setae on disto-dorsal margin (Fig. 12 B–C).

Operculum (Fig. 12C). As long as wide distal margin concave with small simple distal setae.

Ovigerous females.

Slightly smaller than males; mean TL 2.17 mm, ranges from 1.91 to 2.34 mm (Table 2). Antennule with 10-11 articles (Table 2). Antenna usually shorter than TL (Table 2); lengths of antennal articles 5-6 combined, shorter than half TL (Table 2). Maxillipedal palps cannot be observed on dorsal view, not passing well beyond the basal articles of the antenna.

Variations.

Ianiropsis cf. serricaudis from MCBs shows some degree of variations among the individuals as: 1) overall, the number of antennular articles varied between females and males; females have less articles than males (7-12 versus 9-14, respectively) (Table 2); 2) the total lengths of the antennal articles 5-6 combined is shorter than half TL of females and males (Table 2); 3) long maxillipedal palps can be easily observed in dorsal view on largest adult males (2.43-3.0 mm) (Table 2), but elongated maxillipedal palps can be observed also in males of less size (e.g. 2.17-2.22 mm); and 4) the number of denticles on the lateral margins of the pleotelson, ranged from 2 to 4; the three most common denticles combinations were 3-3 (32%), 4-4 (29%), and 3-4 (14%) (Table 2); sometimes the denticles are much less conspicuous.

Other material examined.

Ianiropsis sp. (USNM 99317): four ovigerous ♀♀, two ♂♂, station II-19 (29.6533 N, -80.38 W), off the coast of Florida, USA, depth 42 m, April-26-1953, identified by Bowman, Thomas E., Smithsonian Institution, National Museum of Natural History. Ianiropsis sp. (USNM 190327): one specimen (damaged, apparently ♀), (37.1017N - -74.5533 W), off the coast of Virginia, USA, depth 180 to 200 m, Sep-01-1976, identified by Virginia Institute of Marine Sciences.