Novorostrum decorocrus Osawa, 1998
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publication ID |
https://doi.org/ 10.1080/0022293042000200059 |
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persistent identifier |
https://treatment.plazi.org/id/E86987BF-FFDE-FFF1-80B3-989B5EC3A281 |
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treatment provided by |
Felipe |
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scientific name |
Novorostrum decorocrus Osawa, 1998 |
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Novorostrum decorocrus Osawa, 1998 View in CoL
( Figures 1–6 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 , Table I)
First zoea
Size. CL 1.68–1.82 mm (mean 1.77 mm; n 55), RSL 7.00– 7.10 mm (mean 7.06 mm; n 55), PSL 4.30–4.40 mm (mean 4.34 mm; n 55).
Carapace ( Figure 1A–C View Figure 1 ). Typical porcellanid; rostral spine extremely long, 3.99 times CL, with numerous spinules along entire length; posterior spines with spinules along entire length, ventral spinules becoming large on proximal part; posteroventral margins of carapace with 11–16 spinules; eyes sessile.
Antennule ( Figure 2A View Figure 2 ). Swollen medially and narrowing distally, with one short seta; endopod bud indistinctly marked; exopod unsegmented, with three aesthetascs and three simple setae distally.
Antenna ( Figure 2B View Figure 2 ). Biramous; endopod fused with protopod, bearing one subterminal plumose seta, distal apex sharply pointed; exopod slender, tapering distally, approximately 1.3 times as long as endopod, with one or two spinules on distal half of mesial margin.
Mandible ( Figure 2C View Figure 2 ). Asymmetrically dentate, incisor processes each with several strong and small teeth, molar processes serrate or spinose, palp buds absent.
Maxillule ( Figure 2D, E View Figure 2 ). Coxal endite with nine or 10 (usually 10) simple/ plumodenticulate setae; basial endite with seven stout spines bearing several small denticles marginally and three or four (usually four) plumodenticulate setae submarginally;
endopod unsegmented, with 1+1 setae, subdistal seta simple, very short (sometimes absent), distal seta plumodenticulate, long, stout.
Maxilla ( Figure 2F View Figure 2 ). Coxal endite bilobed, proximal lobe with nine or 10 plumose/ plumodenticulate setae, distal lobe with six or seven (usually seven) plumodenticulate setae; basial endite bilobed, proximal lobe with nine or 10 (usually 10) plumodenticulate setae, distal lobe with 10 or 11 (usually 11) simple/plumodenticulate setae; endopod unsegmented, with 3+4 sparsely plumose setae; scaphognathite with 8–10 plumose setae on anterior and lateral margins, and five or six (usually five) plumose setae on posterior margin.
First maxilliped ( Figure 2G View Figure 2 ). Biramous; coxa naked; basis with 2+2+2–3+3 simple setae on ventral margin; endopod five-segmented, first to fourth segments with 3, 3, 3, 4–5 (usually five) simple/sparsely plumose setae on ventral margins, respectively, first to third segments with fine setules on dorsodistal margin, fifth segment with eight or nine plumodenticulate setae distally and one plumose seta at dorsoproximal angle; exopod incompletely two-segmented, distal segment with four plumose natatory setae terminally.
Second maxilliped ( Figure 2H View Figure 2 ). Biramous; coxa without setae; basis with two setae on ventrodistal margin; endopod four-segmented, first and second segments each with two simple/sparsely plumose setae on ventral margin, third segment with 1+2 simple/sparsely plumose setae each situated at median and distal parts of ventral margin, fourth segment with five plumodenticulate setae distally and one plumose seta at dorsoproximal angle, fine setules present on dorsodistal margin of second segment and dorsomedian margin of third segment; exopod as in first maxilliped.
Third maxilliped ( Figure 2I View Figure 2 ). Small, biramous, unsegmented buds.
Pereiopods ( Figure 2J View Figure 2 ). Small unsegmented buds.
Abdomen ( Figure 1B, D View Figure 1 ). Five somites; fifth somite longest; second to fifth somites with pair of short simple setae near posterolateral angles and distinct serration on posterodorsal margin; third to fifth segments with pair of posterolateral spines; pleopods absent.
Telson ( Figure 1B, D–I View Figure 1 ). Longer than broad; posterior margin produced into broad trapezoid, with five pairs of long, stout plumose setae bearing distinct hooklets (spinules) distally ( Figure 1G–I View Figure 1 ), hooklets more remarkable on lateral two pairs; lateral angles each with single stout spine and one short plumose seta (anomuran hair) ( Figure 1E View Figure 1 ); posteromedian region narrow, slightly concave, bearing setules ( Figure 1F View Figure 1 ); dorsal surface with two pairs of short plumose setae along midline; anal spine present.
Colour in life. Carapace, abdomen, telson and appendages essentially transparent; median gastric region red-brown; dorsal and ventral margins of rostrum and posterior spines pale orange; orange and/or red-brown chromatophores present on mandibles, proximal part of maxilla, first to fifth abdominal somites and proximal part of telson.
Second zoea
Size. CL 2.10–2.25 mm (mean 2.20 mm; n 55), RSL 12.38–13.00 mm (mean 12.65 mm; n 53), PSL 3.60–5.80 mm (mean 4.44 mm; n 54).
Carapace ( Figure 3A–C View Figure 3 ). Rostral spine more elongate than in previous stage, 5.75 times CL; posteroventral margins of carapace with 5–11 (usually seven to nine) small spinules; eyes now stalked.
Antennule ( Figure 4A View Figure 4 ). Biramous; protopod swollen proximally, with two short plumose setae on median lateral margin and with three or four short plumose setae near junction of exopod; endopod slender, naked, fused with protopod; exopod with five rows of marginal aesthetascs numbering 3–4, 4–5, 3, 2–3, 2 from proximal to distal, distal apex with two or three (usually three) aesthetascs plus three or four simple setae.
Antenna ( Figure 4B View Figure 4 ). Endopod greatly lengthened, approximately 1.8 times longer than exopod, with one short plumose seta near distal apex (sometimes absent), distal apex sharply pointed; exopod with one or two spinules on subdistal mesial margin.
Mandible ( Figure 4C View Figure 4 ). Similar to first zoea, no palp buds.
Maxillule ( Figure 4D–F View Figure 4 ). Coxal endite with 10 or 11 simple/plumodenticulate setae marginally; basial endite with seven or eight (usually eight) stout spines marginally and three or four plumodenticulate setae submarginally; endopod unchanged.
Maxilla ( Figure 4G View Figure 4 ). Coxal endite with 11+7–8 plumose/plumodenticulate setae; basial endite with 10+10–12 simple/plumodenticulate setae; endopod unchanged; scaphognathite with 19–22 marginal plumose setae.
First maxilliped ( Figure 4H View Figure 4 ). Coxa and basis same as in first zoea; endopod five-segmented, setal formula (ventral or distal setae+dorsal plumose seta), 3+I, 3+I, 3+I, 5+I, 8–9+I; exopod indistinctly two-segmented, distal segment with 12 plumose natatory setae, proximal two setae short.
Second maxilliped ( Figure 4I View Figure 4 ). Coxa naked; basis with two simple setae on ventrodistal margin; endopod four-segmented, with setation of 2, 2+I, (1+2)+I, 5–6+I (dorsal plumose seta of second segment rarely absent); exopod with 11 or 12 (usually 12) plumose natatory setae, proximal two setae short.
Third maxilliped ( Figure 4J View Figure 4 ). Endopod elongate, swollen, indistinctly segmented, without setae; exopod small, naked.
Pereiopods ( Figure 4K View Figure 4 ). Well formed but unsegmented; first and fifth pereiopods bifid distally, showing chelate appearance.
Abdomen ( Figure 3B, D View Figure 3 ). Similar to first zoea; pair of biramous pleopod buds ( Figure 4L View Figure 4 ) present on second to fifth abdominal somites, respectively.
Telson ( Figure 3B, D–I View Figure 3 ). Similar to first zoea except for posteromedian margin with a pair of short plumodenticulate setae and dorsal surface with four pairs of short plumose setae as illustrated.
Colour in life. Similar to first zoea. Carapace with scattered small red or orange chromatophores; antennal endopod and pereiopods with orange chromatophores.
Megalop
Size. CL 1.52–1.83 mm (mean 1.71 mm; n 55), TL 2.97–3.20 mm (mean 3.06 mm; n 55).
Carapace ( Figure 5A–D View Figure 5 ). Elongate oval-shaped, approximately 1.6 times as long as broad; dorsal surface covered with minute denticles and scattered short simple setae. Rostrum ( Figure 5B View Figure 5 ) broad, subtriangular, with shallow median groove; anterior margin bearing few minute denticles.
Pterygostomian flap ( Figure 5C View Figure 5 ) differentiated from carapace by faint demarcations, anterior margin rounded. Thoracic sternites ( Figure 5D View Figure 5 ) as illustrated; third thoracic sternite strongly depressed, median lobe broad, weakly marked, with shallow depression, lateral lobes strongly produced anteriorly, narrow, rounded.
Antennule ( Figure 6A View Figure 6 ). Peduncle three-segmented; first (proximal) segment broad, with small granules on anterolateral margin and row of simple/plumose setae on lateral margin and ventral surface; second and third segments with few short simple/plumose setae; flagellum biramous; endopod two-segmented, proximal segment slightly longer than distal segment, with seven or eight simple setae, distal segment with 10 simple setae; exopod sixsegmented, with row of aesthetascs on second to fifth segments, numbering proximal to distal, 0–3+7–8, 7–9+4–5, 3+3, 3, respectively, fourth and fifth segments with two or three short simple setae, distal segment with one long and short simple setae.
Antenna ( Figure 6B View Figure 6 ). Peduncle four-segmented (first segment illustrated incompletely), with few short setae; second segment with small rounded lobe on anterodistal margin; third and fourth segments apparently unarmed; flagellum composed of 16–20 articles (usually 19 or 20), each with four to eight simple setae or naked on distal margin as illustrated.
Mandible ( Figure 6C View Figure 6 ). Subsymmetrically scoop-like; palp three-segmented, proximal segment with two simple setae, median segment naked, distal segment with 13–15 serrate setae terminally.
Maxillule ( Figure 6D View Figure 6 ). Coxal endite with 28–32 simple/plumodenticulate setae, lower part with one long simple seta; basial endite with 15–17 spines and 11–15 plumose/ plumodenticulate setae terminally or subterminally, lateral margin near proximal part of endopod with one long plumose seta; endopod unsegmented, with two short plumose setae on distomesial margin.
Maxilla ( Figure 6E View Figure 6 ). Coxal endite bilobed, with 38–44+18–20 simple/plumodenticulate setae, but exact number of setae difficult to count due to extremely high density; basial endite bilobed, with 18–21+29–38 simple/plumodenticulate setae; endopod unsegmented, with three to six setae on distal half; scaphognathite with 46–58 marginal plumose setae and four simple setae or dorsal and ventral surfaces.
First maxilliped ( Figure 6F View Figure 6 ). Coxal and basial endites with 14–18 and 34–43 simple/ plumodenticulate setae, respectively; endopod unsegmented but with slightly constricted parts and 4–11 setae on mesial margin; exopod with one to eight plumose setae on distal margin and five to eight plumose setae on lateral margin.
Second maxilliped ( Figure 6G View Figure 6 ). Biramous; coxa with six or seven plumose setae; basis with five or six plumose setae; endopod five-segmented, proximal segment (ischium) fused to basis, with setation of 5–6, 8–9, 4–6, 23–29, 19–24 from proximal to distal (in distal two segments, stout serrate setae included, exact count of setae difficult because of their high density); exopod two-segmented, proximal segment with five to seven short and four to six long simple/plumose setae, distal segment (flagellum) with six to nine terminal plumose setae.
Third maxilliped ( Figure 6H View Figure 6 ). Biramous; coxa with 11–14 plumose setae and two serrate setae; basis narrow, with three or four plumose setae; endopod five-segmented; ischium with seven or eight long plumose and 14–18 short simple setae, distolateral projection weakly produced; merus with broad, rounded lobe on mesial margin, and 14–16 long plumose and 10–17 short simple setae; carpus with 11–15 long plumose, eight or nine serrate and 10–14 short simple setae; propodus with 17–20 long plumose, six to nine serrate and five to eight short simple setae; dactyl with 14–16 long plumose setae, four to six serrate setae and one to three short simple setae; exopod elongate, overreaching distal margin of ischium, incompletely two-segmented, with one or two proximal and zero to two terminal short simple/plumose setae.
Pereiopods ( Figure 5A, E–G View Figure 5 ). All legs fully developed, with numerous short simple/plumose setae and covered with minute denticles. Cheliped (first pereiopod) approximately as long as carapace, flattened dorsoventrally, with scattered short plumose setae on dorsal surface; carpus with one large proximal tooth and four to six small teeth on dorsoflexor margin, all teeth acutely pointed, extensor margin slightly serrated; propodus with rows of small acute teeth on extensor and flexor margins, dorsal surface with several small denticles; dactylus with row of small acute teeth on flexor margin, dorsal surface with small denticles. Ambulatory legs (second to fourth pereiopods) flattened, with scattered short plumose and simple setae on lateral and dorsal surfaces, lateral surfaces of merus, carpus and propodus with small denticles; merus with row of small teeth on extensor and flexor margins; carpus slightly crenulated on extensor margin; propodus with three to five small movable spines on flexor margin, lateral spine of distal pair largest, extensor margin nearly smooth; dactylus with three small movable spines on flexor margin. Fifth pereiopod short, slender, chelate; propodus with six to nine long, distally curved, serrate setae and scattered short simple/plumose setae as illustrated. No male or female gonopores.
Abdomen ( Figure 5A View Figure 5 ). Six somites, with numerous short simple/plumose setae on dorsal surface, as illustrated. Pleopods ( Figure 5H–K View Figure 5 ) present on second to fifth somites, biramous; endopods increasing in length posteriorly, with three or four minute hooks and zero to three marginal short plumose setae; exopods equal in size, bearing marginal plumose setae, numbering proximal to distal, 10–14, 12–15, 12–14, 11–14.
Tail fan ( Figure 5L View Figure 5 ). Telson incompletely divided into seven plates with notches and faint demarcations; anteromedial plate more distinctly marked than others; anterolateral plates small, indistinct but recognizable with shallow lateral depression; intermediate and posterior plates recognizable with notches and more distinctly marked than anterolateral plates; posterior margin with 18–22 (usually 9–11 pairs) long plumose setae, plus 6–10 (usually three to five pairs) submarginal simple setae; dorsal surface with scattered short simple/plumose setae as illustrated. Uropods biramous, endopod with 11–13 plumose setae on distal margin and four or five simple setae on distolateral margin, exopods with 15–18 plumose setae and one simple seta marginally.
Colour in life. Body and pereiopods generally transparent, carapace and abdomen with scattered orange or red chromatophores; antennule, antenna and third maxilliped with orange chromatophores; chelipeds and ambulatory legs with orange-red coloured spines, denticles and fringe of setae.
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