Scyllarides squammosus (H. Milne Edwards, 1837)

Palero, Ferran, Genis-Armero, Rebeca, Hall, Michael R. & Clark, Paul F., 2016, DNA barcoding the phyllosoma of Scyllarides squammosus (H. Milne Edwards, 1837) (Decapoda: Achelata: Scyllaridae), Zootaxa 4139 (4), pp. 481-498 : 487-495

publication ID	https://doi.org/ 10.11646/zootaxa.4139.4.2
publication LSID	lsid:zoobank.org:pub:247A52DC-530C-46FB-A985-ED8E0444CF09
DOI	https://doi.org/10.5281/zenodo.5626505
persistent identifier	https://treatment.plazi.org/id/038C6004-FFBE-FF83-FF34-FF3CFEE467C6
treatment provided by	Plazi
scientific name	Scyllarides squammosus (H. Milne Edwards, 1837)
status

Treatment

Scyllarides squammosus (H. Milne Edwards, 1837) View in CoL

Stage VI (NHMUK 2015.3279)

Measurements ( Fig. 2 View FIGURE 2 A). TL = 11.7 mm; CW = 6.3 mm; CL = 9.0 mm.

Cephalic shield ( Fig. 2 View FIGURE 2 A). Spindle-shaped, longer than wide (CL/CW = 1.42), maximum width located to mid length.

Antennule ( Fig. 2 View FIGURE 2 B). Peduncle 3-segmented, each segment with similar length. Distal segment biflagellated, accesory flagellum half the length of primary flagellum. Primary flagellum with 7 rows of aesthetascs on inner margin.

Antenna ( Fig. 2 View FIGURE 2 B). Biramous, endopod 2-segmented. The inner ramus reaching the anterior end of first antennular segment.

Maxillule ( Fig. 2 View FIGURE 2 C). Uniramous, palp (endopod) absent. Coxal endite with 4 setae (three strong terminal cuspidate setae). Basal endite with 4 setae (three long strong terminal cuspidate setae).

Maxilla ( Fig. 2 View FIGURE 2 D). Rudimentary bud with small elongation at distal end. Triangular shape. Endites, endopod and scaphognathite not differentiated.

First maxilliped ( Fig. 2 View FIGURE 2 D). Undeveloped, present as small conical protuberance.

Third maxilliped ( Fig. 2 View FIGURE 2 A). Uniramous. Five segmented (ischio-merus fused to basis). Without ventral coxal spine.

Pereiopods ( Fig. 2 View FIGURE 2 A). Biramous, without coxal or subexopodal spines. Exopods of pereiopods 1–4 flagellated distally with ~12–14 annulations, each annulation bears a pair of plumose natatory setae. Pereiopod 5 underdeveloped, small single segment with conical shape. Distal end nearly reaching the telson.

Pleon ( Fig. 2 View FIGURE 2 E). Unsegmented. Pleopods or uropods absent.

Stage VII (NHMUK 2015.3280)

Measurements ( Fig. 3 View FIGURE 3 A). TL = 14.9 mm; CW = 8.2 mm; CL = 12.0 mm.

Cephalic shield ( Fig. 3 View FIGURE 3 A). Pear-shaped, longer than wide (CL/CW = 1.46), maximum width located to mid length.

Antennule ( Fig. 3 View FIGURE 3 B). Primary flagellum with 8 rows of aesthetascs on inner margin.

Antenna ( Fig. 3 View FIGURE 3 B). Longer than first antennular segment. Endopod 2-segmented, reaching the middle of the second antennular segment. Exopod retracts and widens, becoming triangular-shaped.

Maxillula ( Fig. 3 View FIGURE 3 C). Coxal endite with 6 setae, 4 located in apical position and 2 in basal position. Basal endite with 6 setae (3 terminal, elongated, with strong structure and serrated laterally).

Maxilla ( Fig. 3 View FIGURE 3 D). Small tapered elongation becomes less evident, reduced in length. Triangular shape.

First maxilliped ( Fig. 3 View FIGURE 3 D). Unchanged.

Third maxilliped ( Fig. 3 View FIGURE 3 A). Unchanged.

Pereiopods ( Fig. 3 View FIGURE 3 E). Exopods of pereiopods 1–4 distally flagellated with 15–17 annulations. Pereiopod 5 underdeveloped, with conical base at thorax. Distal end reaches beyond telson.

Pleon ( Fig. 3 View FIGURE 3 E). Pleon non-segmented, uropods present as small uniramous buds. Telson more developed, longer than previous stage.

Stage VIII (NHMUK 2015.3 281)

Measurements ( Fig. 4 View FIGURE 4 A). TL = 19.5 mm; CW = 10.6 mm; CL = 15.5 mm. Cephalic shield ( Fig. 4 View FIGURE 4 A). Pear-shaped, longer than wide (CL/CW = 1.46), maximum width located to mid length.

Antennule ( Fig. 4 View FIGURE 4 B). Accessary flagellum reaches middle length of primary flagellum. Primary flagellum with 8–9 rows of aesthetascs on inner margin.

Antenna ( Fig. 4 View FIGURE 4 B). Reaches proximal end of third antennular segment. Endopod now 3-segmented. Significant increase in length of second segment. Triangular outer ramus becomes shorter and stouter.

Maxillule ( Fig. 4 View FIGURE 4 C). Coxal endite with 6 setae, 4 located at distal portion and 2 located in basal position. Basal endite with 7 setae (3 terminal, elongated).

Maxilla ( Fig. 4 View FIGURE 4 D). Still underdeveloped, but wider than in previous stages.

First maxilliped ( Fig. 4 View FIGURE 4 D). Present as a minute protuberance. Diameter of conical base significantly larger than previous stages.

Pereiopods ( Fig. 4 View FIGURE 4 E). Exopods of pereiopods 1–4 distally flagellated with 16–18 annulations. Pereiopod 5 now 2-segmented, and reaching beyond telson.

Pleon ( Fig. 4 View FIGURE 4 E). Somite divisions incomplete. Uropods are biramous.

Stage IX (NHMUK 2015.3282)

Measurements ( Fig. 5 View FIGURE 5 A). TL = 23.6 mm; CW = 13.8 mm; CL = 19.0 mm.

Cephalic shield ( Fig. 5 View FIGURE 5 A). Pear-shaped, longer than wide (CL/CW = 1.37). Slightly narrower than thorax.

Antennule ( Fig. 5 View FIGURE 5 B). Primary flagellum with 9–10 rows of aesthetascs on inner margin.

Antenna ( Fig. 5 View FIGURE 5 B). Exceeds second antennular segment. Four segments remain but the exopod now reduced to small tip.

Maxillule ( Fig. 5 View FIGURE 5 C). Coxal endite with 7 setae (3 longer setae in distal portion). Basal endite with 9 setae (3 terminal, long and serrated).

Maxilla ( Fig. 5 View FIGURE 5 D). Similar to previous stages, but scaphognathite acquires rudimentary rectangular shape.

First maxilliped ( Fig. 5 View FIGURE 5 D). Adopting more tubular form with length significantly larger than previous stages.

Pereiopods ( Fig. 5 View FIGURE 5 A, E). Exopods of pereiopods 1–4 distally flagellated. Pereiopod 5 now 3-segmented and reaching beyond telson.

Pleon ( Fig. 5 View FIGURE 5 E). Divisions of somites becomes evident. Pleopods present, underdeveloped and biramous. Uropods biramous, length of internal lobe half than outer lobe. Telson unchanged.

Stage X (NHMUK 2015.3283)

Measurements ( Fig. 6 View FIGURE 6 A). TL = 31.0 mm; CW = 18.5 mm; CL = 24.0 mm.

Cephalic shield ( Fig. 6 View FIGURE 6 A). Pear-shaped, longer than wide (CL/CW = 1.29), but relatively wider than previous stages.

Antennule ( Fig. 6 View FIGURE 6 B). Accessory flagellum longer than half length of primary flagellum. Primary flagellum with 10–12 rows of aesthetascs on inner margin.

Antenna ( Fig. 6 View FIGURE 6 B). Five-segmented and reaching beyond third antennular segment. Second antennal segment develops a lateral extension (lateral process) while first segment becomes cylindrical.

Maxillule ( Fig. 6 View FIGURE 6 C). Coxal endite with 13 setae. Basal endite with 9 setae (3 long, strong and serrated).

Maxilla. ( Fig. 6 View FIGURE 6 D). Scaphognathite slightly differentiated, without setae, flattened and reduced in size.

First maxilliped ( Fig. 6 View FIGURE 6 D). Like previous stage.

Second maxilliped ( Fig. 6 View FIGURE 6 A). Five-segmented, with rudimentary and unarmed minute exopod bud present.

Third maxilliped ( Fig. 6 View FIGURE 6 A, F). Uniramous. Five segmented (ischio-merus fused to basis). Without ventral coxal spine. Distal part of propodus and dactylus densely setose.

Pereiopods ( Fig. 6 View FIGURE 6 E, G). Pereiopods 1–4 biramous, without coxal or subexopodal spines. Exopods of pereiopods 1–4 flagellated distally with 17–19 annulations, each annulation bears a pair of plumose natatory setae. Pereiopod 5 with four-segmented endopod, without setae. Distal end reaches beyond telson.

Pleon ( Fig. 6 View FIGURE 6 E). Five-segmented (five somites plus telson, somite 1 not differentiated). Pleonites 2–5 with a pair of biramous pleopods, unsegmented and unarmed. Uropods biramous and incipiently segmented, but not outreaching posterior margin of telson. Telson rounded posteriorly, without processes or teeth.

Stage XI (NHMUK 2015.3284)

Measurements (Fig. 7A). TL = 39.0 mm; CW = 23.1 mm; CL = 29.0 mm.

Cephalic shield (Fig. 7A). Pear-shaped, longer than wide (CL/CW = 1.26), maximum width located to mid length.

Antennule (Fig. 7B). Primary flagellum with 12–14 rows of aesthetascs on inner margin.

Antenna (Fig. 7B). Almost equal in length to antennule. Lateral expansion on the second segment widens while segment 4 gets narrower.

Maxillule (Fig. 7C). Coxal endite with 14 setae (2 terminal setae considerably longer and stronger). Basal endite with 9 setae (3 long, strong and serrated).

Maxilla (Fig. 7D). Similar to previous stage, but scaphognathite more differentiated, without setae, flattened and slightly expanded anteriorly and posteriorly.

First maxilliped (Fig. 7D). Further developed.

Pereiopods (Fig. 7E). Biramous, without coxal or subexopodal spines. Exopods of pereiopods 1–4 flagellated distally with>18 annulations, each annulation bears a pair of plumose natatory setae. Pereiopod 5 with 5 segments present, segment 2 with rudimentary exopod.

Pleon (Fig. 7E, F). Segmented, with six pleonites plus telson. Pleonites 2–5 with a pair of biramous and unsegmented pleopods each, without appendix interna. Presence of two dorsal spines on pleonites 3–4. Biramous uropods outreaching posterior margin of telson.

Stage XII (NHMUK 2015.3285)

Measurements ( Fig. 8 View FIGURE 8 A). TL = 51.0 mm; CW = 26.5 mm; CL = 36.0 mm

Cephalic shield ( Fig. 8 View FIGURE 8 A). Pear-shaped, longer than wide (CL/CW = 1.35), but proportionally longer than previous stage.

Antennule ( Fig. 8 View FIGURE 8 B). Accessory flagellum extended, equal in length to primary flagellum. Primary flagellum with 13–15 rows of aesthetascs on inner margin.

Antenna ( Fig. 8 View FIGURE 8 B). Longer than antennule. Segments fully developed. Lateral expansion on second segment directed anteriorly (more developed than previous stage). Last antennal segment leaf-shaped.

Maxillule ( Fig. 8 View FIGURE 8 C). Coxal endite with 14 setae (2 terminal setae considerably longer and stronger). Basal endite with 11 setae (3 long, strong and serrated).

Maxilla ( Fig. 8 View FIGURE 8 D). Fully developed, scaphognathite considerably expanded anteriorly and posteriorly. Endopod becomes triangular.

First maxilliped ( Fig. 8 View FIGURE 8 D). Fully developed and markedly biramous.

Second maxilliped ( Fig. 8 View FIGURE 8 A). Exopod bud elongated.

Third maxilliped ( Fig. 8 View FIGURE 8 A). Gill buds present, with one pleurobranch, one arthrobranch and epipod with podobranch.

Pereiopods ( Fig. 8 View FIGURE 8 E). Pereiopod 1 with one pleurobranch, one arthrobranch and epipod with podobranch. Pereiopods 2–4 with two pleurobranchs, one arthrobranch and epipod with podobranch. Pereiopod 5 with one pleurobranch. Pereiopod 5 now 6-segmented. Basis with exopod bud and ischium and merus are fused.

Pleon ( Fig. 8 View FIGURE 8 E, F). Fully segmented with 4 pairs of segmented pleopods. Posterolateral margin of the pleura of somites 2, 3, 4 and 6 ended with acute spine. Dorsally, somites 4 and 5 bear a strong median spine. Pleopods biramous, segmented and without setae, endopod with appendix interna. Biramous uropods outreaching posterior margin of telson.

Morphometric analyses showed that total length of the larvae follows an exponential growth in late stages of development (see Table 2 View TABLE 2 ). The ratio of cephalic width over the total length increased during phyllosoma development up to a maximum value of CW/TL = 0.61 at around 30 mm TL (see Fig. 9 View FIGURE 9 ) and then decreased again in the sub-final and final stages (CW/ TL = 0.43 + 0.011 TL–0.00018 TL2; r2 = 0.999). The relative growth of CL and CW during larval development in phyllosoma larvae assigned to Scyllarides squammosus was found to follow a power law equation (CW = 0.84 CL0.96), with a high correlation coefficient (r2 = 0.996). However, the confidence interval for the exponent parameter comprised the value b = 1 (0.91–1.01), which indicates that the growth of CW does not show a significantly allometric pattern.

Stage = Stage of development; N = Sample size; Range = range of lengths per stage; Mean = Average total length per stage. Total length (TL) measured from the anterior margin of the cephalic shield between the eyes to the posterior margin of the telson.