Michelea imperieusae, Poore And D, 2015

Poore And D, Gary C. B., 2015, Micheleidae (Crustacea: Decapoda: Axiidea): new family, generic and species synonymies, three new Australian species, and new records, Memoirs of Museum Victoria 73, pp. 95-105 : 98

Michelea imperieusae sp. nov.

Figure 1

Michelea sp. MoV5530.—McCallum, 2012: 57.

Material examined. Holotype. Western Australia, RV Southern Surveyor Imperieuse L23 transect (18°27.37'S – 18°27.43'S, 120°08.41'E – 120°08.41'E), 80–81 m, 19 Jun 2007 (stn SS05/2007/082), NMV J55702 (male, cl 3.5 mm, fixed in 96% ethanol).

Diagnosis. Gills fully developed. Pleopods 2–5 with 20/5, 19/10, 20/15 and 20/15 marginal lamellae on endopods/exopods respectively. Telson tapering, length 1.1 width. Maxilliped 3 ischium with obsolete crista dentata, exopod longer than ischium; merus with mesial tooth.

Description. Cephalothorax 0.25 total length, about 1.8 times as long as greatest depth; rostrum acute, sharply narrowing from broad base, slightly depressed distally, about 0.7 as long as eyestalks; cervical groove weakly defined, reaching 0.65 length of cephalothorax; longitudinal setal-row level with lateral margin of eyestalk, of 6 setae; marginal setal-row of 2 setae at base of eyestalk.

Pleomere 1 with dorsolateral longitudinal setal-row of 6 setae. Pleomeres 2–4 with transverse setal-row of about 6 setae near lateral posterior margin; pleomere 5 with transverse setal-row of 8 setae; all somites also with groups of long simple setae, none with marginal setal-rows. Pleomere 6 with 2 transverse setal-rows of 3 setae.

Antennule with elongate waisted article 1, 0.4 times length of cephalothorax; articles 2 and 3 subequal, each about 0.25 length of article 1; flagella each of 10 articles, longer than peduncle. Antenna with distinct articulating scaphocerite, about third length of article 2; article 4 reaching to middle of article 2 of antenna 1; article 5 short; flagellum of 20 articles, more than twice as long as peduncle.

Mandible, maxillules, maxillae, maxillipeds 1 and 2 typical of genus. Maxilliped 3 ischium with obsolete crista dentata; merus with strong mesial tooth; exopod 1.7 times ischium length.

Chelipeds unknown.

Pereopod 2 merus–propodus with lower marginal rows of long setae; carpus 0.55 length of merus; propodus little longer than carpus with setal-row of 7 short setae; fixed finger cutting edge with 4 short spiniform setae; dactylus longer than fixed finger, with 3 short spiniform setae on distal half of cutting edge; each finger with corneous tip. Pereopod 3 propodus twice as long as wide, with 4 spiniform setae on lower margin, plus 2 on distal-lower and 2 on distal-upper mesial face; and 2 transverse setal-rows of 3 and 2 setae; dactylus with 2 spiniform setae on upper-mesial margin. Pereopod 4 propodus 3 times as long as wide, 9 spiniform setae, some in pairs, on lower mesial face, and 6 on upper margin, and transverse setal-row of 4 setae; dactylus with 3 spiniform setae on upper-mesial margin. Pereopod 5 subchelate; propodus with setae on lower margin; fixed finger with 5 spiniform setae.

Pleopods 1 of male curved mesially, expanded distally, with c. 8 minute hooks, setose around midpoint and laterally, and with 1 simple seta at apex. Pleopod 2 with 20/5 marginal lamellae on endopod/exopod respectively; appendix masculina third length of endopod; appendix interna half length of appendix masculina. Pleopod 3 with appendix interna sac-like, 3 times as long as wide; with 19 lamellae on endopod, 10 on exopod; pleopods 4 and 5 each with 20 lamellae on endopod, 15 on exopod.

Uropodal endopod ovate, 1.6 times as long as wide, with a minute distal tooth; exopod ovate, 1.8 times as long as wide, mesiodistal margin oblique, lateral margin with 5 short spiniform setae. Telson tapering to rounded apex from onequarter length; 1.15 times as long as wide.

Gills fully developed.

Distribution. Western Australia, 18°S, 120°E, 80 m.

Etymology. Imperieusae , from Imperieuse Reef, near the type locality, noun in genitive case.

Remarks. Although the chelipeds are missing we are confident that this is a new species closest to M. hortus . It differs in having more pleopodal lamellae ( M. hortus has only four or five marginal lamellae on the pleopodal endopods and none on the exopods), and more elongate uropodal rami (endopod and exopod 1.4 and 1.6 times as long as wide respectively) and telson (as wide as long).