Makarasphaera amnicosa, Bruce, 2005

Bruce, Niel L., 2005, New sphaeromatids (Crustacea: Isopoda: Sphaeromatidea) from coastal and freshwater habitats in New Zealand, Zootaxa 1002 (1002), pp. 1-20 : 12-18

Makarasphaera amnicosa sp. nov. ( Figs 5–8)

Material examined.— Holotype: ♂ (2.6 mm), western end of Ohariu Bay (= ‘Makara Beach’), North Island, 41°13.125’S, 174°42.374’E, 2 January 2004, small, flowing, freshwater stream, ~15 metres from pebble beach berm, under rocks, coll. N.L., J. and S. Bruce ( NIWA 4073 ).

Paratypes: 4♂ (2.8 [dissected], 2.8 [maxillipeds], 2.6, 2.5 mm), 3♀ (non­ovig. 2.8, 2.7, 2.7 mm), manca (1.6 mm), same data as holotype ( NIWA 4074 ) .

Additional material: 22 specimens, ♂, ♀♀ and mancas from type locality ( NIWA 4075 ) . 12 specimens, males, females, Cape Palliser , North Island, 41°36.406’S, 175°16.107’E, 23 Nov 2003, west of cape, freshwater seep above highest tide level, coll. N.L. Bruce and Jørgen Olesen ( NIWA 4076 ) .

Description of male. Body about 1.7 times as long as greatest width, strongly vaulted, lateral margins subparallel, widest at pereonite 6; dorsal surfaces smooth. Cephalon anterior margin without distinct transverse ridge, ventral rostral process weakly developed.

Head and pereonite 1 subequal in length, unornamented; pereonites 2–7 subequal in length (in lateral view); posterior margins of pereonites without transverse submarginal dorsal ridge. Coxae without evident sutures, progressively increasing in size posteriorly. Pleon sublateral ‘keys’ weakly developed. Pleotelson without ornamentation; posterior margin wide, subtruncate.

Antennule peduncle article 1 2.0 times as long as wide, about 2.2 times as long as article 2; posterior margin of articles 1 and 2 with 1 and 2 brush­tipped sensory setae; article 3 about 1.4 times as long as article 2, 0.6 times as long as article 1, 3.1 times as long as wide; flagellum 6­articled, extending to posterior of pereonite 1, about 1.8 times as long article 3. Antenna peduncle article 1 short, about 0.2 times as long as article 2; articles 2–5 becoming progressively longer; article 4 about 1.9 times as long as article 3, about 0.7 as long as article 5; flagellum 1.1 times as long as peduncle, extending to pereonite 3, with 11 articles.

Epistome anteriorly narrowly rounded, without lateral constriction. Left mandible incisor with 3 cusps, lacinia mobilis with 3 cusps, spine row of 4 serrate spines; molar process with gnathal surface circular, surface prominently nodular; palp articles 1 and 2 subequal in length, article 2 distolateral margin with 4 distally biserrate setae, becoming progressively longer distally; article 3 with 7 serrate setae, terminal seta being largest. Maxillule mesial lobe with 4 long, strongly pectinate RS and 1 shorter simple RS, lateral lobe with 9 peripheral RS on gnathal surface, twelfth seta set between these; 4 proximomesial RS serrate, distolateral RS smooth. Maxilla lateral lobe and middle lobe each with 7 curved finely nodular RS, mesial lobe with 9 plumose and CP RS. Maxilliped endite lateral margin sinuate, distal margin oblique, with 1 simple acute RS at sublateral angle, 2 blunt simple RS and 6 CP RS; single mesial CP RS distal to coupling hook; distal mesial surface of with mass of long scale­setae; palp articles 2–4 weakly lobed; articles 2–5 with 6, 12, 9 and 12 setae respectively.

Pereopod 1 robust, basis about 2.9 times as long as greatest width, approximately 1.7 times as long as propodus; ischium 1.1 times as long as propodus, 2.1 times as long as greatest width, superior margin with 1 proximal and one mid­distal acute short simple RS, distal inferior margin with sparse scale­setae; merus about 0.6 as long as ischium, 1.2 times as long as greatest width, superior distal angle with 1 acute simple RS, inferior margin with sparse scale­setae, inferior distal angle with 2 short and 1 long simple setae; carpus approximately as 0.8 long as wide, inferior margin 0.5 times as long as merus, inferior distal angle with 1 RS and 2 short simple setae; propodus 3.0 times as long as greatest width, inferior margin with simple setae and scales, inferodistal angle with 2 biserrate RS and 1 distally plumose seta; dactylus 0.4 times as long as propodus, unguis inferior margin with prominent serrate cuticular scales, secondary unguis straight, simple. Pereopods 2–7 elongate and slender in comparison to pereopod 1. Pereopod 2 basis 3.6 times as long as greatest width, inferodistal angle with single simple seta, superior margin with 3 widely spaced palmate setae; ischium 0.7 times as long as basis, 3.6 times as long as greatest width, proximal superior margin with 2 single acute RS, inferior distal margin with sparse short simple setae; merus 0.7 times as long as ischium, superior distal angle with 1 long distally biserrate RS and 1 short seta, inferior distal angle with 1 long simple setae; carpus 1.3 times as long as merus, 3.2 times as long as wide, anterodistal angle with 1 biserrate and 1 simple setae, inferior margin with prominent acute scales midlength; propodus 0.8 times as long as ischium, 5.5 times as long as wide, superior distal angle with 2 setae, inferior margin with serrate scales, with 2 simple setae. Pereopods 5–7 similar, longer than pereopods 2 and 3. Pereopod 7 basis 5.0 times as long as greatest width, inferodistal angle with 1 simple setae, superior margin proximally with few serrate scales, with many widely­spaced small sensory palmate seta; ischium 0.7 times as long as basis, 3.6 times as long as greatest width, superior margin with abundant scale setae, with 1 short proximal acute RS, inferior distal angle with 1 seta; merus 0.6 times as long as ischium, 2.3 times as long as wide, superior distal margin with 1 distally biserrate and 1 short simple RS, inferior margin with 2 simple seta, inferodistal angle with l long simple seta; carpus as long as merus, 2.8 times as long as wide, superior distal angle with 3 biserrate and 1 simple RS, inferodistal margin with 1 biserrate and 1 plumose RS; propodus 0.7 times as long as ischium, 5.0 times as long as wide, superior distal angle with 2 setae, inferior margin distally with 2 simple RS.

Penial processes separate, mutually adjacent, 8.6 as long as basal width, with acuminate apex.

Pleopod 1 exopod and endopod with 19 and 15 PMS respectively; endopod 0.8 as long as exopod, 1.5 times as long as greatest width, proximal lateral margin weakly convex; exopod with oblique axis, distal margin subtruncate; peduncle mesial margin extended, with 3 coupling hooks. Pleopod 2 exopod and endopod with 21 and 13 PMS respectively; appendix masculina 4.5 times as long as basal width, 1.5 times as long as endopod, distal quarter abruptly narrowed, apex narrowly rounded; endopod mesial margin concave, lateral margin weakly convex; exopod 1.4 times as long as endopod, distal margin subtruncate. Pleopod 3 exopod and endopod with 20 and 11 PMS respectively. Pleopod 4 both rami lacking any trace of ridges, without transverse suture; endopod 0.6 as long as exopod, with marginal fine simple setae and single distal plumose seta; exopod glabrous. Pleopod 5 both rami lacking any trace of ridges, without transverse suture; exopod with 2 weakly developed scale patches, margin of both rami without setae. Uropod exopod 0.6 as long as endopod, margins smooth, with fringe of short setae scale­setae, distally narrowly rounded; endopod 3.2 times as long as wide, lateral margin convex, narrowing distally to acute apex, mesial margin weakly sinuate.

Female: Body shape similar to that of male. Brood­pouch structure not known.

Remarks. The species is distinguished by the generic characters.

Distribution. Lower North Island, New Zealand, at Makara (near Wellington) and Cape Palliser on the southeastern coast.

Habitat. The species is found in freshwater seeps and fast­flowing small streams above the reach of tidal influence, but within range of salt spray during storm periods. All specimens were under pebbles and stones, or under pieces of wood; usually in groups, occasionally singly.

Etymology. The epithet is derived from the amnicus (Latin—‘of a stream’) alluding to the habitat at the type locality.