Msangia mussida, Stępień, Anna & Błażewicz-Paszkowycz, Magdalena, 2013

Stępień, Anna & Błażewicz-Paszkowycz, Magdalena, 2013, Four new species and two new genera of Metapseudidae (Crustacea: Tanaidacea: Apseudomorpha) from Australian coral reefs, Zootaxa 3717 (4), pp. 559-592 : 584-590

Msangia mussida n. sp.

Figs 15–18

Material examined: Holotype, female (MTQ W 34248), HI 10-31, 23°15'44.28"S, 151°55'32.16"E, Heron I., depth 6.4 m, 18 November 2010, coll. V.N. Ivanenko, M. Wakeford. Paratypes: 18 females (MTQ W 34249), HI 10-31; 2 female (MTQ W 34250), HI 10-009E, 23°25'53.76"S, 152°2'57.48"E Heron I., Sykes Reef W, reef slope, coral rubble on sand, depth 12 m, 13 November 2010, coll. C. Buxton. 2 females (MTQ W 34251) HI 10-009D the same lacality as holotype, but reef flat, depth 14 m.

Diagnosis. Body 10.6 times as long as wide, carapace 1.3 times as long as wide, eyes present with ommatidia. Pleonites shorter than pereonite 6. Antenna peduncle with four articles; inner margin of proximal antennular peduncle smooth. Chela twice as long as wide. Pereopod 1-3 robust, with merus wider than long; pereopod 1-2 with two and one spine on ventral margins. Uropod with four and three segments in endopod and exopod, respectively.

Etymology. The species name is given in relation to its habitat, which was a head of a live coral of the family Mussidae .

Description of female. Body ( Figs. 15 A, B) 1 mm long, 10.6 times as long as wide. Carapace 14% of total body length; rostrum rounded; eye with dark pigment. Pereonites rectangular; pereonite 1 half as long as wide, with three setae laterally; pereonites 2, 3 and 4 0.7 times as long as wide, with three simple lateral setae; pereonites 5 and 6 similar in length, 0.6 times as long as wide, with two simple lateral setae. Pleon 40% of total body length; all pleonites similar in length, half as long as wide and shorter than pereonite 6, with one fine lateral seta; pleotelson 0.6 times as long as all pleonites together.

Antennule ( Fig. 17 A) peduncle article 1 margin smooth, three times as long as wide, with one outer and inner simple seta distally; article 2 0.3 times as long as article 1, with three simple setae on outer distal margin and with one simple seta on inner margin; article 3 with one simple setae on outer and inner margin distally; article 4 with one simple setae on inner margin. Outer flagellum with three segments; segment 1 with simple seta and one aesthetasc distally; segment 2 with two simple setae and one aesthetasc distally; segment 3 with three simple setae. Inner flagellum with two segments; segment 1 with two, segment 2 with four simple setae distally.

Antenna ( Fig. 17 B) peduncle with four articles; article 1 almost as long as wide, with rounded flat apophysis and with minute setae along outer margin; article 2 half as long as article 1, with minute setae along outer margin and in inner distal corner; article 3 2.2 times as long as wide, with one simple distal seta; article 4 partially fused to article 3 with one simple distal seta.

Mouthparts. Right mandible ( Fig. 16 A) bearing incisor with blunt tooth, setiferous lobe with two bifurcated and one robust trifurcated setae; palp ( Fig. 16 C) with three articles; article 1 1.5 times as long as wide, naked; article 2 1.6 times as long as article 1, with two pinnate setae distally; article 3 0.3 times as long as article 2, with one long, pinnate seta, and three short, simple setae distally. Left mandible ( Fig. 16 B) with blunt incisor; lacina mobilis with six denticulation; setiferous lobe with two pinnate setae. Molar not seen. Maxillule inner endite ( Fig 16 E) with four simple setae; outer endite ( Figs. 16 D, D’) with nine terminal spines. Maxilla ( Fig. 16 F) outer lobe of movable endite with three simple setae distally and two simple setae subdistally; inner lobe of movable endite with five simple setae distally; outer lobe of fixed endite with four simple setae and two pinnate setae distally; inner lobe of fixed endite with some simple distal setae and row of five simple subdistal setae. Labium ( Fig. 16 G) lobe with four combs of simple setae along outer margin; palp with fine lateral setules and one simple seta distally. Maxilliped palp ( Fig. 16 I) article 1 0.8 times as long as wide, with one simple seta on inner margin and with one strong simple seta on outer margin distally; article 2 twice as long as article 1, with row of simple setae on inner margin and with one simple seta on outer distal margin; article 3 0.7 times as long as article 2, with row of five strong setae on inner margin; article 4 0.6 times as long as article 3, with row of six simple setae distally. Endite ( Fig. 16 H) with three spines, one simple and one pinnate setae on inner margin, with two couling-hooks on outer margin, and with three simple setae, one spine, one forked and one pinnate setae distally.

Cheliped ( Fig. 17 D) basis 1.2 times as long as wide, with two simple ventral setae (one central, one distal); exopodite absent; merus 2.5 times as long as wide, with three simple setae on ventral margin; carpus 4.8 times as long as wide, with two simple setae ventrally and comb of five simple setae on distal ventral corner, and with two simple distodorsal setae; propodus 1.2 times as long as wide, with one ventral and two dorsal simple setae and one simple setae near dactylus insertion; fixed finger half as long as wide, with five simple setae on cutting edge and four simple setae on ventral margin; dactylus 0.6 times as long as propodus with crenulated inner margin; unguis 0.3 times as long as dactylus, with three processes on inner margin.

Pereopod 1 ( Fig. 18 A) basis 2.6 times as long as wide, with two penicillate setae on dorsal margin; ischium half as long as wide, with one simple ventral seta; merus 1.2 times as long as wide, with one simple distal seta on each of ventral and dorsal margins; carpus 0.6 times as long wide, with three spines and four simple setae on distal margin; propodus 1.4 times as long as carpus, with two spines and one pinnate setae on ventral margin, and with one penicillate seta, one simple seta and two spines on dorsal margin; dactylus together with unguis 1.2 times as long as propodus, with one simple seta on dorsal margin; unguis almost as long as dactylus.

Pereopod 2 ( Fig. 18 B) basis 2.6 times as long as wide, with two penicillate setae on dorsal margin and two simple setae distally; ischium twice as long as wide, with one simple ventral seta; merus 1.2 times as long as wide, with one simple seta on ventral margin; carpus 0.7 times as long as wide, with three spines and two simple setae distally; propodus 1.2 times as long as carpus, with two spines on ventral margin, and with two spines, one pinnate and one simple setae near dactylus insertion; dactylus together with unguis 1.2 times as long as propodus, with simple seta on dorsal margin, unguis 0.7 times as long as dactylus.

Pereopod 3 ( Fig. 18 C) similar to pereopod 2, but basis 2.3 times as long as wide; unguis 0.4 times as long as dactylus.

Pereopod 4 ( Fig. 18 D) basis 2.5 times as long as wide, with two penicillate setae on dorsal margin, and with one simple ventrodistal seta; ischium 0.6 times as long as wide, with one simple seta on each of ventral and dorsal distal margins; merus 1.2 times as long as wide, with one simple seta on dorsal margin, and with two simple setae on ventral margin; carpus as long as merus, with two spines and two simple setae distally; propodus as long as carpus, with one spine and one simple and four pinnate setae distally; dactylus together with unguis 1.1 times as long as propodus, with one ventral margin and one dorsal fine seta; unguis 0.8 times as long as dactylus.

Pereopod 5 ( Fig. 18 E) basis 2.6 times as long as wide, with two penicillate and two simple setae on dorsal margin and with two simple ventral setae; ischium as long as wide, with two dorsal and one ventral simple setae; merus 1.7 times as long as wide, with one dorsal and one ventral simple setae; carpus 1.3 times as long as wide, with one dorsal and one ventral simple seta; propodus 2.5 times as long as wide, 1.6 times as long as carpus, with one penicillate dorsal seta, one simple ventral seta and with four pinnate setae near dactylus insertion; dactylus together with unguis 0.6 times as long as propodus, with one dorsal and one ventral simple setae; unguis 0.3 times as long as dactylus.

Pereopod 6 ( Fig. 18 F) basis 2.5 times as long as wide, with one simple seta and two penicillate setae on dorsal margin, and with two simple setae on ventral margin; ischium 1.2 times as long as wide, with two dorsal and one ventral simple setae; merus twice as long as wide, with one dorsal and two ventral simple setae; carpus 1.8 times as long as wide, with one dorsal and three ventral simple setae; propodus 3.2 times as long as wide, 1.4 times as long as carpus, with one penicillate dorsal seta and with four distal pinnate setae; dactylus together with unguis 0.7 times as long as propodus, with one dorsal and one ventral seta; unguis 0.7 times as long as dactylus.

Pleopods ( Fig. 17 C) all similar; basis twice as long as wide, naked; endopod with two articles, first article with one distal simple seta, second article with two simple setae; exopod with one article, with three simple setae.

Uropods ( Fig. 17 E) basis 1.5 times as long as wide, with two simple distal setae on outer margin; endopod with four segments; segments 2 and 3 each with simple distal seta, segment 4 with three simple distal setae; exopod with three segments, segment 3 with two simple distal setae.

Remarks. Msangia mussida n. sp. is the fourth member of the genus. M. larvoides Băcescu, 1976 occurring in the vicinity of Mbudya Island (Indian Ocean) has five segments in the endopod and two segments in the exopod of the uropod, while Msangia bacescui Gutu, 2006 inhabiting corral rubble in coasts of Tanzania has five and three segments in the uropod endopod and exopod respectively. The only species that has the same number of segments in the uropod, i.e. four in the endopod and three in the exopod, is M. tarangensis Gutu & Angsupanich, 2006 , which was recorded from coral rubble on sand in the Andaman Sea (Gutu & Angsupanich 2006). From the last species M. mussida can be distinguished by the presence of three setae on the endopod of the pleopod (five in M. tarangensis ). The new species also has quite robust pereopods, in which the carpus is wider than long in contrast to M. tarangensis . In addition, the new species has two and one spines respectively on the ventral margin of the carpus and the propodus of the first two pairs of pereopods, while there are three and two spines on those articles respectively in M. tarangensis .

Figures

FIGURE 15. Msangia mussida n. sp., holotype female. A body dorsal view; B body lateral view. Scale line = 1 mm.

FIGURE 16. Msangia mussida n. sp., A right mandible; B left mandible; C palp of mandible; D maxillule outer endite; D’ maxillule outer endite (upper view); E maxillule inner endite; F maxilla’; G labium; H maxilliped endite; I maxilliped. Scale line = 0.1 mm.

FIGURE 17. Msangia mussida n. sp., A antennule; B antenna; C pleopod; D cheliped; E uropod. Scale line = 0.1 mm.

FIGURE 18. Msangia mussida n. sp., A pereopod 1; B pereopod 2; C pereopod 3; D pereopod 4; E pereopod 5; F pereopod 6. Scale line = 0.1 mm.