Microrchestia bousfieldi Lowry &amp; Peart 2010, sp. nov.
Creators: name: Lowry, J. K.
name: Peart, R.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Protorchestiidae
Microrchestia
Microrchestia bousfieldi

description: <i>Microrchestia bousfieldi</i> sp. nov. (Figs 1–6) <b>Type material.</b> Holotype, male, 10 mm length, AM P80876, South West Rocks Creek, South West Rocks, New South Wales, Australia (30°53.50’S 153°01.78’E) in mangroves, under and in rotting logs, intertidal, Anna Murray, Rachael Evans &amp; Penny Coleing, 30 April 1999 (NSW 1560). Paratypes: female, 9 mm length, AM P80877; 19 specimens, AM P80878, (same locality as holotype). <b>Additional material examined.</b> 6 specimens, AM P80879, South West Rocks Creek, Trial Bay, New South Wales, Australia (30°53.24’S 153°02.09’E), under bark of dead Avicennia marina branches, P.B. Berents, K.B. Attwood and P. Coleing, 2 May 1999 (NSW 1613). <b>Type locality.</b> South West Rocks Creek, South West Rocks, New South Wales, Australia (30°53.50’S 153°01.78’E). <b>Etymology.</b> Named for Ed Bousfield in recognition of his insightful work on talitrid amphipods. <b>Description.</b> Based on holotype, male, 10 mm, AM P80876. Head. Eye large (greater than 1/3 head length). Antenna 1 elongate (from midpoint to end of article 5 of antenna 2). Antenna 2 up to half body length; peduncular articles narrow; peduncular article 5 longer than article 4. Mandible left lacinia mobilis 4-dentate. Maxilliped palp article 2 with distomedial lobe; article 4 distinct, small. Pereon. Gnathopod 1 not sexually dimorphic; subchelate; posterior margin of merus, carpus and propodus each with lobe covered in complex setae in both male and female; propodus subrectangular; palm transverse; dactylus subequal in length to palm. Gnathopod 2 sexually dimorphic; subchelate; coxal gill slightly lobate, smaller than gill 3; basis slightly expanded; posterior margin of merus, carpus and propodus each without lobe covered in complex setae; carpus triangular, reduced (enclosed by merus and propodus); carpus posterior lobe absent, not projecting between merus and propodus; palm acute; strongly toothed, incised or sinuous; with bimodal protuberance near dactylar hinge, protuberence with robust setae; without midpalmar sinus; posterodistal corner with socket; dactylus subequal in length to palm, not attenuated distally. Pereopods 2–4 coxae wider than deep. Pereopods 3–7 simplidactylate. Pereopod 3 coxal gill slightly lobate, smaller than gill 4. Pereopod 4 subequal or slightly shorter than pereopod 3; coxal gill slightly lobate, similar size to gill 5; carpus similar in length to pereopod 3 carpus, dactylus similar to pereopod 3 dactylus. Pereopod 5 coxal gill lobate, larger than gill 6; propodus distinctly longer than carpus. Pereopod 6 not sexually dimorphic; slightly shorter than pereopod 7; coxa posterior lobe inner view posteroventral corner with small cusp, posterior margin (inner view) oblique to ventral margin, posterior lobe without ridge, with 1–2 marginal setae; coxal gill lobate. Pereopod 7 slightly sexually dimorphic; basis lateral sulcus absent, posterodistal lobe rounded, produced downwards almost to merus; distal articles (merus and carpus) slightly expanded; merus posterior margin evenly rounded; carpus subrectangular. Pleon. Pleopods all well developed. Pleopods 1–3 peduncle not expanded. Pleopod 1 peduncle without marginal setae; biramous, outer ramus subequal in length to peduncle; inner ramus subequal in length to outer. Pleopod 2 biramous, outer ramus longer than peduncle. Pleopod 3 biramous, outer ramus longer than peduncle. Epimeron 2 subequal in length to epimeron 3. Epimeron 3 posterior margin smooth, without setae, posteroventral corner narrowly rounded; ventral margin robust setae absent. Uropod 1 not sexually dimorphic; peduncle with 7 robust setae on peduncle, distolateral robust seta present, small (less than 1/4 length of outer ramus), with simple tip; rami without ventral robust setae; inner ramus subequal in length to outer ramus, with 4–5 robust setae on the margins; outer ramus without marginal robust setae. Uropod 2 not sexually dimorphic; peduncle with 4 robust setae; inner ramus subequal in length to outer ramus, with 2 marginal robust setae; outer ramus without marginal robust setae. Uropod 3 peduncle with 2 robust setae; ramus shorter than peduncle, linear, narrowing, without marginal setae, with 4 to 5 apical robust setae. Telson as broad as long, entire, dorsal midline vestigial or absent, with 2 apical robust setae per lobe. Female (sexually dimorphic characters). Based on paratype, female, 11 mm, AM P80877. Eye medium (1/ 5–1/3 head length). Gnathopod 1 propodus subrectangular. Gnathopod 2 mitten-shaped; basis slender; posterior margin of merus, carpus and propodus each with lobe covered in complex setae; carpus well developed (not enclosed by merus and propodus), posterior lobe present, projecting between merus and propodus; palm obtuse, smooth, posterodistal corner without spine; dactylus shorter than palm. Pereopod 7 basis posterodistal lobe absent; distal articles (merus and carpus) slender. Oostegites longer than wide, weakly setose, setae with multifurcated tips. Uropod 1 peduncle with 8 robust setae; with 3 robust setae on the margins. Telson with 3–6 robust setae per lobe. <b>Habitat.</b> Intertidal in mangroves, under and in rotting logs. <b>Remarks.</b> <i>Microrchestia bousfieldi</i> appears to be most similar to <i>M. macrochela</i> (Bousfield, 1971), based on the shape of the palm of male gnathopod 2, but whereas <i>M. bousfieldi</i> has two distinct humps along the palm, <i>M. macrochela</i> has only one. In addition <i>Microrchestia bousfieldi</i> lacks robust setae on the posterior lobe of coxa 6 (present in <i>M. macrochela</i>); it has more setae on the peduncles and rami of uropods 1 and 3 than does <i>M. macrochela</i>; and it has only apical robust setae on the telson (apical and marginal in <i>M. macrochela</i>). <i>Microrchestia bousfieldi</i> differs significantly from <i>M. watsonae</i> in the shape of male gnathopod 2 which is strongly sculptured with few marginal robust setae on the palm (palm with a shallow distal plate and the main palmar area is lined with robust setae in <i>M. watsonae</i>). In addition, <i>M. bousfieldi</i> has no setae on the posteroventral margin of coxa 6 and the corner forms a small cusp (with marginal setae and rounded corner in <i>M. watsonae</i>); the posteroventral corner of epimeron 3 is narrowly rounded (forming a small subacute tooth in <i>M. watsonae</i>); the ramus of uropod 3 has more robust setae than that of <i>M. watsonae</i> and the telson is as long as broad (longer than broad in <i>M. watsonae</i>). No male of <i>M. similis</i> has been reported, but the females differs in the posterior margin of pereopod coxa 6 which is has no marginal setae in <i>M. bousfieldi</i> (setae present in <i>M. similis</i>); in the posterior margin of epimeron 3 which lacks setae and the posteroventral corner which is narrowly rounded (setae present and posteroventral corner with a small subacute spine in <i>M. similis</i>); uropod 3 peduncle and ramus slightly more setose in <i>M. bousfieldi</i>. <b>Distribution.</b> Australia. Southwest Rocks, northern New South Wales.
description: Published as part of <i>Lowry, J. K. &amp; Peart, R., 2010, The genus Microrchestia (Amphipoda: Talitridae) in eastern Australia, pp. 21-38 in Zootaxa 2349 (1)</i> on pages 23-30, DOI: 10.11646/zootaxa.2349.1.2, http://zenodo.org/record/5309249
description: {"references": ["Bousfield, E. L. (1971) Amphipoda of the Bismarck Archipelago and adjacent Indo-Pacific islands (Crustacea). Steenstrupia, 1, 255 - 293."]}