Macrostylis peteri Riehl 2025, sp. nov.

Macrostylis peteri Riehl sp. nov. Materials Type status: Holotype. Occurrence: occurrenceDetails: in sediment; catalogNumber: NMV J 60800; occurrenceRemarks: free-living; recordedBy: G. C. B. Poore; individualCount: 1; sex: female; lifeStage: adult; reproductiveCondition: non-ovigerous; preparations: whole animal (ETOH); disposition: in collection; occurrenceID: 101BB144-53A6-50F1-9725-E96107890E93; Taxon: scientificName: Macrostylis peteri Riehl; kingdom: Animalia; phylum: Arthropoda; class: Malacostraca; order: Isopoda; family: Macrostylidae; genus: Macrostylis; specificEpithet: peteri; taxonRank: species; scientificNameAuthorship: Riehl; vernacularName: Peter's Long-stalked Sea Slater; nomenclaturalCode: ICZN; Location: higherGeography: Indian Ocean; continent: Australia; stateProvince: Western Australia; county: Australia; municipality: Ningaloo South; locality: SS 07 / 2005 Station 23 T 1 700; verbatimDepth: 715.17; verbatimCoordinates: 22°3'46.44''S, 113°43'22.8''E; verbatimLatitude: 22°3'46.44''S; verbatimLongitude: 113°43'22.8''E; decimalLatitude: - 22.0629; decimalLongitude: 113.723; Identification: identifiedBy: Torben Riehl; dateIdentified: 2011; Event: samplingProtocol: R / V SOUTHERN SURVEYOR cruise SS 02 / 2005, Smith McIntyre Grab; eventDate: 24. 07. 2005; habitat: sediment; fieldNumber: SS 07 / 2005 23 T 1 700; Record Level: institutionID: http://grscicoll.org/institution/museum-victoria; institutionCode: NMV; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: occurrenceDetails: in sediment; catalogNumber: NMV J 46837; occurrenceRemarks: free-living; recordedBy: G. C. B. Poore; individualCount: 1; sex: female; lifeStage: adult; reproductiveCondition: non-ovigerous; preparations: whole animal (ETOH); disposition: in collection; occurrenceID: BB12D00E-7FBD-5784-A097-35387E727389; Taxon: scientificName: Macrostylis peteri Riehl; kingdom: Animalia; phylum: Arthropoda; class: Malacostraca; order: Isopoda; family: Macrostylidae; genus: Macrostylis; specificEpithet: peteri; taxonRank: species; scientificNameAuthorship: Riehl; vernacularName: Peter's Long-stalked Sea Slater; nomenclaturalCode: ICZN; Location: higherGeography: Indian Ocean; continent: Australia; stateProvince: Western Australia; county: Australia; municipality: Ningaloo South; locality: SS 07 / 2005 Station 23 T 1 700; verbatimDepth: 715.17; verbatimCoordinates: 22°3'46.44''S, 113°43'22.8''E; verbatimLatitude: 22°3'46.44''S; verbatimLongitude: 113°43'22.8''E; decimalLatitude: - 22.0629; decimalLongitude: 113.723; Identification: identifiedBy: Torben Riehl; dateIdentified: 2011; Event: samplingProtocol: R / V SOUTHERN SURVEYOR cruise SS 02 / 2005, Smith McIntyre Grab; eventDate: 24. 07. 2005; habitat: sediment; fieldNumber: SS 07 / 2005 23 T 1 700; Record Level: institutionID: http://grscicoll.org/institution/museum-victoria; institutionCode: NMV; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence: occurrenceDetails: in sediment; catalogNumber: NMV J 60803; occurrenceRemarks: free-living; recordedBy: G. C. B. Poore; individualCount: 1; sex: male; lifeStage: subadult; reproductiveCondition: immature; preparations: whole animal (ETOH); disposition: in collection; occurrenceID: 8F9890F4-961E-50E9-BCDA-BB1DC55F618C; Taxon: scientificName: Macrostylis cf. peteri Riehl; kingdom: Animalia; phylum: Arthropoda; class: Malacostraca; order: Isopoda; family: Macrostylidae; genus: Macrostylis; specificEpithet: cf. peteri; taxonRank: species; scientificNameAuthorship: Riehl; vernacularName: Peter's Long-stalked Sea Slater; nomenclaturalCode: ICZN; Location: higherGeography: Indian Ocean; continent: Australia; stateProvince: Western Australia; county: Australia; municipality: Ningaloo North; locality: SS 07 / 2005 Station 33 T 2 400; verbatimDepth: 429.392; verbatimCoordinates: 21°58'0.85''S, 113°47'20.4''E; verbatimLatitude: 21°58'0.85''S; verbatimLongitude: 113°47'20.4''E; decimalLatitude: - 21.9669; decimalLongitude: 113.789; Identification: identifiedBy: Torben Riehl; dateIdentified: 2011; identificationRemarks: species identity unclear due to juvenile stage and lack of genetic data; Event: samplingProtocol: R / V SOUTHERN SURVEYOR cruise SS 02 / 2005, Smith McIntyre Grab; eventDate: 24. 07. 2005; habitat: sediment; fieldNumber: SS 07 / 2005 33 T 2 400; Record Level: institutionID: http://grscicoll.org/institution/museum-victoria; institutionCode: NMV; basisOfRecord: PreservedSpecimen Description Description non-ovigerous (preparatory) female Body (Figs 40, 41, 42) shape broadest in anterior half, narrowing posteriorly, subcylindrical; length 2.3–2.4 mm, 3.5–3.8 width, tergite and Plt surfaces hirsute, rest of body less setose. Ventral projections (Fig. 40 B, Fig. 41 B) present; Prn 1 spine acute and prominent; Prn 2 spine directed ventrally, acute, prominent, located medially; Prn 3 spine acute, prominent, medially positioned on; Prn 4 spine directed posteriorly, acute, prominent, closer to posterior segment border; Prn 5 spine acute, prominent, positioned closer to posterior segment border; Prn 6 spine acute, prominent, positioned closer to posterior segment border; Prn 7 spine prominent, acute; spines 3-7 directed posteroventrally. Ceph (Fig. 40 A, Fig. 41 C) length 0.45–0.66 width, 0.10–0.15 body length; frontal furrow present, laterally bent anteriorly, medially straight; posterolateral setae present, flexibly articulated. Fossosoma (Fig. 40 A) length 0.85–0.89 width, 0.24 body length; ventral surface without carina, lateral tergite margins confluent, posterolaterally setose. Prn 1-3 (Fig. 40 A, B) posterolaterally with simple seta respectively. Prn 4 (Fig. 40 A) width 1.1–1.2 pereonite 5 width, length 0.3–0.39 width; with well developed collum, medially widest, with relatively slightly projecting posterolateral margin; lateral margins sinuoid, narrowest anteriorly at collum, widest at coxal insertions, progressively narrowing towards posterolateral protrusions; posterior tergite margin setose, setae flexibly articulated, not extending beyond posterolateral margin; posterolateral margins projecting, contracting laterally, tapering; posterolateral setae robust, spine-like, articulating on pedestals. Prn 5 (Fig. 40 A) length 0.48–0.5 width, 1.0–1.4 Prn 4 length; posterior tergite margin setose, setae flexibly articulated, not extending beyond posterolateral margin; posterolateral margins rounded; posterolateral setae robust, spine-like, articulating on pedestals. Prn 6 (Fig. 40 A) length 0.53–0.57 width, 1.02–1.08 Prn 5 length; posterior tergite margin setose; setae flexibly articulated, not extending beyond posterolateral angles; posterolateral margin projecting, rounded; posterolateral setae robust, flexibly articulated. Prn 7 (Fig. 40 A) length 0.42–0.45 width; posterior tergite margin setose, setae flexibly articulated, not extending beyond posterolateral margin. Posterolateral margin projecting posteriorly, tapering, subangular; posterolateral setae robust, (149) flexibly articulated. Plt (Fig. 40) length 0.23–0.24 body length, 1.4 width, slightly narrower than Prn 7, near-elliptic; posterior margin at uropod insertions straight to convex; apex convex, spatulate, length 0.15–0.18 Plt length, with 12 pappose setae positioned on and around apex; pleopodal cavity width 0.76 Plt width; setal ridges visible in dorsal view; longitudinal trough width 0.41 Plt width; anal opening caudally in the trough, exposed and superficial, tilted posteriorly relative to frontal plane. A 1 (Fig. 43 A, D) length 0.22 head width, 0.13 A 2 length, width 0.53 A 2 width; Art decreasing in size from proximal to distal, relative Art length ratios 1.0: 0.85: 0.55: 0.49: 0.33; Art L / W ratios 2.0, 2.9, 1.8, 1.9, 1.8; all Art longer than wide; Art 1 longest and widest; terminal article with 1 aesthetascs; aesthetasc with intermediate belt of constrictions. A 2 (Fig. 43 A, D) length 0.4 body length; C length shorter than width; basis length exceeding width, more than twice C length; ischium longer than C; merus and carpus each longer than C, basis and ischium combined; carpus shorter than merus length; (218) flag with 7 Art. Md (Fig. 44) with lateral setae; molar process length greater than incisor length; both incisor processes oligodentate with dorsal and ventral subdistal teeth that partly enclose lacinia, left Md incisor process with four cusps, lacinia mobilis robust, similar to incisor process, with four cusps; right Md incisior process with three cusps, lacinia mobilis spine-like, smaller than left lacinia. Mxp (Fig. 43 F-H) basis length 4 width; endite distally with four fan setae, medioventrally setose; palp wider than endite, Art 2 wider than Art 1; ischium distomedially with one seta, shorter than Art 3, Art 4 distomedial extension present, Art 5 absent; epipod length 3.2 width, 1.0 coxa-basis length. P 1 (Fig. 45) length 0.46 body length; ischium dorsal margin with five simple setae; merus dorsal margin with six setae: five simple, long, one more robust, bifid apically, ventral margin with four medially biserrate, distally sensillate setae; carpus dorsally with three setae: one simple, long, one broom, one bifurcate; dactylus medially-subdistally with three sensillae, terminal claw length 0.28 dactylus length. P 2 (Fig. 45 B) length 0.42 body length. Ischium dorsally with 4-5 simple setae submarginally; merus dorsally with 4-5 simple, long setae submarginally and one bifurcate seta distodorsally, ventrally with four medially biserrate, distally sensillate setae, on ventral margin, with 1-2 minute, simple distomedially; carpus dorsally with 2-3 setae: 0-1 simple, one broom, one bifurcate, ventrally with 3-4 setae: 2-3 medially biserrate, distally sensillate, one slender, simple, asetulate; dactylus medially-subdistally with three sensillae. P 3 (Fig. 45 C) length 0.48 body length. Ischium dorsal lobe subtriangular; dorsal margin proximally with four asetulate setae; apex with one prominent, robust, sensillate, bifid, str