The larval development of Maja squinado and M. brachydactyla (Decapoda, Brachyura, Majidae) described from plankton collected and laboratory-reared material Author Guerao, Guillermo Author Pastor, Elena Author Martin, Jocelyne Author Andrés, Mireia Author Estévez, Alicia Author Grau, Amàlia Author Duran, Juana Author Rotllant, Guiomar text Journal of Natural History 2008 2008-09-30 42 33 - 34 2257 2276 http://dx.doi.org/10.1080/00222930802254755 journal article 10.1080/00222930802254755 1464-5262 5223797 Maja squinado Herbst, 1788 ( Figures 1–12 ) Zoea I Size: RDL51.93¡ 0.03 mm ; CL51.18¡ 0.02 mm ; CW51.42¡ 0.02 mm . Carapace ( Figure 1A and B ) . With long, naked dorsal spine, curved distally and backwards; long rostral spine, similar length antennae; lateral spines present and well developed; each lateroventral margin with one densely plumose ‘‘anterior seta’’, followed by five additional sparsely plumose setae; one pair of anterodorsal setae and one pair of posterodorsal setae present; eyes sessile. Antennule ( Figure 3A ) . Uniramous, smooth and conical; endopod absent; exopod unsegmented with four terminal aesthetascs and one minute seta. Antenna ( Figure 3D ) . Biramous, protopod (spinous process) very long with two rows of spinules; endopod bud approximately 1/3 the size of spinous process; unsegmented exopod shorter than the spinous process, with two unequal subterminal spinulose setae. Mandible . Incisor and molar processes differentiated; mandibular palp absent. Maxillule ( Figure 4B ) . Coxal endite with seven setae; basial endite with seven setae (three cuspidate+four plumodenticulate); endopod two-segmented, proximal segment with one seta, distal segment with two subterminal and four terminal setae; exopodal seta absent. Maxilla ( Figure 5A ) . Coxal endite bilobed with 3+4 setae; basial endite bilobed with 5+4; unsegmented endopod not bilobed, with five terminal setae; exopod Table 1. Morphometrical and meristic differences in zoeal stages of Maja squinado , M. brachydactyla , M. previous studies.

Feature	M. squinado	M. brachydactyla	M. brachydactyla M. brachydactyla		M. goltziana	M. crispata
(Present study)	(Plankton; present (Laboratory; present (Clark, 1986)			( Paula, 1988 )	(Rodríguez,
study)	study)	2002)
Zoea I
RDL (mm)	1.93¡0.03	1.94¡0.06	1.87¡0.05	1.95	2.03–2.15	1.4–1.5
CL (mm)	1.18¡0.02	1.15¡0.03	1.12¡0.04	nd	1.00–1.08	nd
Carapace pv (s)	1+5	1+5	1+6	1+6	1+5	1+5
Antennule (a+s)	4+1	4+2	4+2	4+2	4+1	4+0
Maxilla
scaphognathite (s)	11–12+1	11+1	11+1	11–13+1	15	11–13+1
Maxilliped 1
coxa (s)	1	1	1	nd	nd	1
Maxilliped 2
coxa (s)	0	0	0	nd	nd	0
endopod (s)	0,1,4	0,1,4	0,1,4	0,1,4	0,1,6	0,1,6
Pleon (s)	2,2,2,2,2	2,2,2,2,2	2,2,2,2,2	2,2,2,2,2	2,2,2,2,2	2+2,2,2,2,2
Zoea II
RDL (mm)	2.19¡0.04	2.22¡0.04	2.02¡0.05	2.10	2.03–2.27	1.61–1.72
CL (mm)	1.41¡0.02	1.33¡0.06	1.30¡0.05	nd	1.19–1.27	nd
Carapace pv (s)	1+7	1+7	1+7	1+7	1+6	1+6
Antennule (a+s)	7+0	7+2	7+2–3	6+3	7+2	8+0
Maxilla
scaphognathite (s)	24–26	21–22	22	21	27	21–23
Pleon (s)	3,2+2,2,2,2,0	3,2+2,2,2,2,0	3,2+2,2,2,2,0	3,2+2,2,2,2,0	3,2+2,2,2,2,0	2+2,2,2,2,2,0

Note: s, setae; a, aesthetascs; nd, not described. Table 2. Morphometrical and meristic differences in the megalopae of Maja squinado , M. brachydactyla , M. previous studies. (scaphognathite) margin with 11–12 plumose setae plus one distal stout plumose process.

Feature	M. squinado	M. brachydactyla	M. brachydactyla	M. brachydactyla	M. goltziana	M. crispata
(Present study)	(Plankton; present	(Laboratory;	(Clark, 1986)	( Paula, 1988 )	( Rodríguez, 2002 )
study)	present study)
CL (mm)	1.88¡0.03	1.70¡0.05	1.67¡0.07	1.4–1.5	1.79–1.91	1.72–1.90
Carapace (sp)	absent	absent	absent	absent	present	present
Antennule (a+s)	0,8+1,4+0,0+1	0,8+1,4+0,0+1	0,8+1,4+0,0+1	0,8+1,4+1	0,9+0,5+0,0+1	0,8+1,4+1
Antenna (s)	1,1,2–3,0,4,3	1,1,3,0,4,3	1,1,3,0,4,3	1,1,3,0,0,4,3	2,1,3,0,0,4,3	1,1,3,0,4,3
Maxillule
Coxal end (s)	11	11	10–11	11	10	11
Basial end (s)	18–19	18	18–19	17	19	17
Maxilla
Coxal end (s)	4–5+5	4–6+5	5+5	5+5	5+5	5+5
Basial end (s)	6+7	6+6	6+6	6+6	6+7	6+6
Scaphognathite (s)	42–45	38–42	40–41	36	48	38–42
Maxilliped 1
Coxal end (s)	7	6	7	8	8	7
Basial end (s)	12	12	12	12	15	12
Epipod (s)	4–5	6	5	5	6	5–6
Maxilliped 2
Endopod (s)	0,1,3,5	0,1,3,5	0,1,3,5	0,1,3,5	0,1,4,6	0,1,3,5
Maxilliped 3
Endopod (s)	10–11,8,5,6,5	11,7,5–6,6,5	11,5–6,5,6,5	11,7,5,7,5	10,5,5,6,5	13,7,5,6,5
Epipod (s)	9–10+3	9+3	8–7+3	7+3	8+0	10+3
Pereiopods 1–5
Coxa (sp)	0,1,1,1,0	0,1,1,1,0	0,1,1,1,0	0,0,0,0,0	0,1,1,1,0	0,1,1,1,0
Isquio (sp)	1,1,1,0,0	1,1,1,0,0	1,1,1,0,0	0,1,1,1,0	0,1,1,1,1	1,1,1,0,0
Dactylus (ssp)	0,2,2,3,3	0,2,2,3,3	0,2,2,3,3	0,2,2,3,3*	0,2,3,2,3*	0,3,3,3,3
Sternum (s)	6	6	6	6	nd	2
Pleopods
Exopod (s)	12–13,12–13,12,11	12,12–13,12,10–11	12,11–12,12,10–11	12,12,10,10	11–12,12,12,10–11	11–12,11–12,10–11,9–10

Note: s, setae; a, aesthetascs; sp, spines; ssp, stout spines; nd, not described; *described from figures. Figure 1. Maja squinado Herbst, 1788 , carapace. (A) first zoea, lateral view; (B) first zoea, frontal view; (C) second zoea, lateral view. Scale bar5500 Mm. Figure 2. Maja squinado Herbst, 1788 , megalopa. (A) megalopa, dorsal view; (B) megalopa, lateral view. Scale bar51000 Mm. Figure 3. Maja squinado Herbst, 1788 , antennule. (A) first zoea; (B) second zoea; (C) megalopa. Antenna. (D) first zoea; (E) second zoea; (F) megalopa. Scale bars5100 Mm. First maxilliped ( Figure 6A ) . Coxa with one seta; basis with nine setae arranged 2+2+2+3; endopod five-segmented with 3,2,1,2,5 (one subterminal and four terminal) setae, respectively; exopod incipiently two-segmented, distal segment with four long plumose natatory setae. Second maxilliped ( Figure 7A ) . Coxa without setae; basis with three setae arranged 1+1+1; endopod three-segmented with 0,1,4 setae, respectively; exopod incipiently two-segmented, distal segment with four long plumose natatory setae. Third maxilliped. Present and biramous. Pereiopods ( Figure 9A ) . Present as small buds, chela bilobed. Pleon ( Figures 11A, B and D ) . With five pleomeres; pleomeres 2 and 3 with one pair of dorsolateral processes; pleomeres 3–5 with a pair of short posterolateral processes; pleomere 1 with two setae, pleomeres 2–5 with one pair of posterodorsal setae; pleopod buds present on pleomeres 2–5. Telson ( Figures 11A, B and D ) . Telson fork with three lateral spines; inner margin with three pairs of serrulate setae. Figure 4. Maja squinado Herbst, 1788 , mandibular palp. (A) megalopa, maxillule. (B) first zoea; (C) second zoea; (D) megalopa. Scale bar of A550 Mm; B–D5100 Mm. Zoea II Size: RDL52.19¡ 0.04 mm ; CL51.41¡ 0.02 mm ; CW51.60¡ 0.02 mm . Carapace ( Figure 1C ) . Antero-median region with four pairs of setae, one pair of setae near the base of the dorsal spine; each lateroventral margin with a densely plumose ‘‘anterior seta’’, followed by seven additional setae (two plumose and five sparsely plumose). Eyes stalked. Antennule ( Figure 3B ) . Exopod now with seven terminal aesthetascs; endopod bud present. Antenna ( Figure 3E ) . Endopod longer than previous stage, reaching middle of the length of spinous process. Mandible . Palp bud present. Maxillule ( Figure 4C ) . Basial endite with nine setae; one exopod long plumose seta on outer margin. Maxilla ( Figure 5B ) . Basial endite with 5+5 setae; scaphognathite with 24–26 marginal plumose setae. First maxilliped ( Figure 6B ) . Exopod distal segment with six long plumose natatory setae. Second maxilliped ( Figure 7B ) . Coxa with epipod bud present; exopod distal segment with six long plumose natatory setae. Third maxilliped ( Figure 8A ) . Biramous bud, epipod rudimentary present. Pereiopods ( Figure 9B ) . Chelipeds and pereiopods 2–5 slightly segmented. Figure 5. Maja squinado Herbst, 1788 , maxilla. (A) first zoea; (B) second zoea; (C) megalopa. Scale bar5100 Mm. Pleon ( Figures 11C and E ). Pleomere 6 differentiated, first pleomere with three long mid-dorsal setae; pleomeres 2–5 with long pleopod buds, endopod buds present. Megalopa Size. CL: 1.88¡ 0.03 mm ; CW: 0.64¡ 0.02 mm . Carapace ( Figure 2A and B ) . Longer than broad; rostrum short, ventrally deflected with median cleft; with lateral prominent carina; with a cardiac and intestinal tubercles. Antennule ( Figure 3C ) . Peduncle three-segmented, with 1,1,1 setae respectively; twosegmented endopod with 0,3 (one subterminal+two terminal) setae; exopod foursegmented, with 0,8,4,0 aesthetascs and 0,1,0,1 setae respectively. Antenna ( Figure 3F ) . Peduncle three-segmented, with 1,1,2–3 setae respectively; flagellum three-segmented, with 0,4,3 setae respectively. Mandible ( Figure 4A ) . Molar portion not differentiated, incisor process saucer-shaped with acute inner margin; palp two-segmented, with four terminal setae on distal segment. Maxillule ( Figure 4D ) . Coxal endite with 11 setae; basial endite with 18–19 setae; endopod unsegmented, with two small distal setae. Figure 6. Maja squinado Herbst, 1788 , first maxilliped. (A) first zoea; (B) second zoea; (C) megalopa. Scale bars5250 Mm. Maxilla ( Figure 5C ) . Coxal endite bilobed, with 4–5+5 setae; basial endite bilobed with 6+7 setae; endopod unsegmented, without setae; scaphognathite with 42–45 plumose marginal setae and five lateral setae. First maxilliped ( Figure 6C ) . Epipod with 4–5 long setae; coxal endite with seven setae; basial endite with 12 setae; endopod unsegmented, without setae; exopod twosegmented, proximal segment with one distal plumose setae, distal segment with 4–5 long terminal plumose setae. Second maxilliped ( Figure 7C ) . Coxa and basis not differentiated, without setae; endopod four-segmented with 0,1,3,5 setae respectively; exopod two-segmented, proximal segment without setae, distal segment with four terminal plumose setae. Third maxilliped ( Figure 8B ) . Epipod elongated with 12–13 setae (three short sparsely plumose+9–10 very long setae); coxa with 7–9 setae; basis with two setae; endopod five-segmented, with 10–11,8,5,6,5 setae respectively, margin of ischium spinosed or crenulate; exopod two-segmented, proximal segment without seta and distal segment with four long terminal plumose natatory setae. Pereiopods ( Figure 10A–C ) . All articles well differentiated; pereiopods 2–4 with coxal process; pereiopods 1–3 with ischial process; dactylus of pereiopods 2–5 with 2,2,3,3 stout short spines ( Figure 10B and C ). Sternum ( Figure 10A ) . Maxillipeds and cheliped sternites fused with six (arranged 2+2+2) setae; all sternal sutures are medially interrupted. Figure 7. Maja squinado Herbst, 1788 , second maxilliped. (A) first zoea; (B) second zoea; (C) megalopa. Scale bars5250 Mm. Pleon ( Figure 12A and B ) . Six pleomeres present; pleomeres 1–6 with 6,8,6,8,8,2 setae; pleomeres 2–5 with posterolateral processes rounded; pleomeres 2–5 each with pair of well developed biramous pleopods. Pleopods ( Figure 12C–F ) . Endopod unsegmented, with three terminal cincinuli, exopod unsegmented with 12–13,12–13,12,11 long marginal plumose natatory setae respectively. Uropods ( Figure 12G ) . Two-segmented, proximal segment without setae, and distal segment with five long plumose setae. Telson ( Figure 12 A and B ) . Square-shaped; dorsal surface with two setae.