Pinjalo pinjalo (Bleeker)

Leis, Jeffrey M, 2008, Larval development in the lutjanid subfamily Lutjaninae (Pisces): the Indo-Pacific genus Pinjalo, Zootaxa 1760, pp. 37-49 : 39-43

Pinjalo pinjalo (Bleeker) ,

Figs. 1 , 2, Table 2

1 flexion and 6 postflexion pelagic larvae, 4.3–7.5 mm. Western Indian Ocean, northwestern continental shelf of Australia: AMS I.26412-007 RV Soela AS 06/82LF stn 9(2) 14.2.82. Western Pacific, Gulf of Thailand: SIO 60-639, RV Naga, 57-25, S10-06-284. Western Pacific Ocean, South China Sea: SIO 60-501, RV Naga, S10-02-110. Western Pacific, Solomon Sea: NSMT-PL 404, RV Shunyo Maru Sta 39 M.

Diagnosis: Pinjalo pinjalo can be distinguished from P. l e w i s i by fin meristics, and the relative lengths of the fin spines ( Table 3). In P. pinjalo , DspI is relatively short (21–49% DspII), and P2sp is about the same size as DspII (85–107% DspII, and 20–33% BL).

Species Dorsal fin DspI P2sp Anal fin

(DspI/DspII %) (P2sp/DspII %)

P. pinjalo XI,14–15 short short III,8–9

(22–49 %) (85–107 %)

P. l e w i s i XII,13 long long III,9–10

(70–90 %) (98–121 %)

Description: Body compressed and deep (39–45% at P1 base, and about 10–12% less at anus), without any clear changes with growth. The gut is coiled and triangular, and in most of the available specimens, the gas bladder is prominent. There is no gap between the anus and anal fin. The head is large (37–44%) and compressed. The eye is large (32–39% HL) and round. The snout is triangular and somewhat shorter than the orbit diameter (60–87% ED). The profile of the head is straight to slightly convex and moderately sloped. The nasal pit is bridged over in the largest specimen (7.5 mm). The mouth is large, reaching to between the anterior edges of the eye and the pupil, and is only slightly oblique – at most, about 35° from the horizontal. Prominent teeth on the premaxillae are present in all specimens, including enlarged, anterior canines.

Spination on the head is extensive and well developed. The inner border of the preopercle has a single upper limb spine in the smallest specimens, increasing to 4 by 7.5 mm, and 2–3 lower limb spines, with only 3 in the 7.5 mm specimen: all are smaller than those on the outer border. The spine at the angle of the preopercle is large and robust (10–16%), and reaches to the base of the pelvic-fin spine. The upper limb of the outer bor- der of the preopercle has only a single spine of moderate length. On the lower limb of the outer preopercle border, there are 3 spines in the smallest larvae, increasing to 5 by 7.5 mm. These spines are graduated in size, with the smallest spines at the anterior end: the posterior-most spine is second in size amongst head spines only to the spine at the angle. The preopercular spines are smooth, except in the 6.3 mm larva (but not the 7.5 mm larva), very fine serrations are present distally on the dorsal surface of the spine at the angle. The anterior most edge of the maxilla also has very fine serrations in most specimens (4 of 5) starting at 5.7 mm. A single, small interopercular spine is present in all specimens. There are no subopercular spines. A single spine on the opercle is present in all specimens. The supraocular ridge is serrate, with 3 spines in the smallest specimen, increasing to 5 spines in the 7.5 mm specimen. A weak, spineless ridge forms on the pterotic at 5 mm, but no frontal ridge is present in the available larvae.

Spination on the pectoral girdle is also well developed. A small postcleithral spine and 3 prominent supracleithral spines as well as a single ventral and a single dorsal posttemporal spine are present in all specimens.

The smallest specimen is in the early flexion stage, and has 6+5 principal caudal rays, DX,12, AII,8 (with the anterior-most ray in both D and A fin transforming to a spine, and with some incipient rays posteriorly), P 2 I,2, and 0 P1 rays. All elements are present in D and A fins by 5.8 mm, but the posterior-most spine is not fully transformed from a soft ray until 6.3 mm. Rays are present in the P1 fin from 5 mm, but the adult complement of 18 is not reached until 7.5 mm. An adult P2 complement of I,5 is present from 5 mm. The fin spines are robust, and have a single leading edge ridge, and two trailing edge ridges. DspII is the longest spine in the dorsal fin (24–34%), but the other spines of this fin are also long, and taper gradually to the length of the fin rays. In contrast to P. l e w i s i, DspI is not particularly long, constituting 22–49% DspII. In the smallest larva, the trailing edges of DspI–VI are coarsely serrate, as are the leading edges of DspI–III, whereas the 7.5 mm larva has serrations on trailing edges of all spines and on leading edges of DspI–V. The anal-fin spines are without serrations in the smallest larva, but by 5 mm, AspI & II have a single leading edge and two trailing edge serrate ridges. AspIII is smooth in all available specimens. The P2sp is of similar length to DspII (84–107% DspII, and 20–33% BL), and has 2 leading edge and 2 trailing edge ridges, all of which are serrate in all available specimens. P2 ray 1 is close to the length of P2sp, extending to near or just past the tip of the spine.

FIGURE Larvae of Pinjalo pinjalo . Unless stated otherwise, in both dorsal and anal fins, the spines have a single leading-edge ridge, and two trailing-edge ridges, and the P2sp has two leading-edge ridges, and two trailing-edge ridges. Not all ridges are visible in the illustrations. Scale bars = 1 mm. A. 4.3 mm early flexion-stage larva from the eastern Indian Ocean over the northwest continental shelf of Australia (AMS I.26412-007). The preopercular spination of the left side was damaged, and some details in the drawing are based on the right side of this specimen. In both dorsal and anal fins, the posterior-most spine is transforming from a soft ray. B. 6.3 mm postflexion-stage larva from the western Pacific Ocean in the Gulf of Thailand (SIO 06-284). Note fine serrations on the anterior edge of the maxilla and on the distal portions of the largest preopercular spine. Some P2 fin rays were broken in the left fin, and their length is shown based on the right fin.

Pigment: Pinjalo pinjalo larvae are not heavily pigmented except on the membrane of the spiny dorsal fin, and over the gut, although pigment does develop on the fore and mid brains. In the smallest specimen, pigment is limited to the following: a single melanophore on each midbrain hemisphere; a diagonal band of melanophores on the membrane of the spiny dorsal fin between spines II–VI; on the ventral edge of the tail, a single melanophore posteriorly on the caudal peduncle, and one at the base of the posterior-most anal-fin rays; a melanophore at the anus and one at the cleithral symphysis; and a thick saddle of pigment over the gas blad- der extending ventrally over the anterior and lateral surfaces of the gut.

The brain pigment increases in density and number of melanophores and spreads so that by 6 mm, there are about 10 melanophores on the dorsal surface of the midbrain and about 2 on the forebrain. By 7.5 mm, a single melanophore forms at the base of the opercular spine and small cluster of melanophores on the dorsal surface of the snout.

No pigment forms on any of the anal or pectoral fins. A single small melanophore at the base of a ventral caudal fin-ray is present in all specimens, and this constitutes the only caudal-fin pigment. In contrast, the dorsal fin is heavily pigmented. On the membrane of the dorsal fin, pigment spreads both posteriorly and ventrally, and increases in density. The pigment is between DspII and VII at 7.5 mm, but remains limited to the distal portions of the fin membrane of spines I–III, although it reaches to near the fin base at more posterior spines. A single melanophore is at the base of DspVII. On the pelvic fins, limited pigment associated with P2 rays 1 or 2 is present in most specimens. This varies from one melanophore to a series of small melanophores along the ray.

From 5.7 mm, there is an internal melanophore on the urostyle in all specimens, although the 7.5 mm specimen has 2 melanophores, and the pigment has spread both laterally and toward the surface.

Ventrally, pigment on the tail remains limited to a single melanophore on the peduncle and a single melanophore at the base of the posterior-most rays of the anal fin. There is no pigment on the ventral surface of the trunk other than an anal melanophore in two specimens (4.3 & 5.8 mm). A single melanophore is present at the cleithral symphysis in all but the 7.5 mm specimen.

Remarks. some of the specimens are relatively faded, and it is possible that the larvae are actually somewhat more heavily pigmented than described here. The head shape of these larvae is very similar to that of 'typical' Lutjanus spp, and there is little indication in the larvae, or in the smallest known settled individual ( Fig. 1 ) of the more rounded head shape typical of adult Pinjalo spp.

Figures

FIGURE 1. Head of 56 mm juvenile Pinjalo pinjalo (USNM 56281, based on photos provided by Jeffrey Williams, USNM) showing head shape, eye location and mouth size and orientation. Scale bar = 5 mm. This is the smallest known post-settlement individual of either Pinjalo species.

Tables

TABLE 2. Meristic and morphometric information on Pinjalo pinjalo larvae. Lower-case Roman numerals in square brackets indicate a soft ray in transition to a spine. Arabic numerals in square brackets indicate base, but not ray, formed. + indicates additional indistinct rays forming, and i indicates incipient rays present. Body Depth (P) and (A), indicate depth at pectoral-fin base and at anus, respectively.

Body Preanal Length Length	Predorsal Length	Head Length	Orbit Diameter	Snout Length	Body Depth (P)	Body Depth (A)	Dsp I Length	DspII Length	P2 sp Length	Dorsal Fin	Anal Fin	Pectoral Fin
Flexion
4.30 2.40	1.50	1.60	0.62	0.45	1.68	1.23	0.29	1.03	0.88	X[i],11[3]	II[i],8[2]	0
Postflexion
5.00 3.13	2.05	2.11	0.71	0.62	2.25	1.61	0.57	1.46	1.46	X[i],15	II,10	12+
5.70 3.70	2.40	2.50	0.80	0.65	2.40	1.80	0.40	1.60	1.60	X[i],14	II[i],9	13+
5.80 3.80	2.30	2.40	0.80	0.70	2.40	1.80	0.50	1.50	1.60	X[i],14	II[i],10	12+
6.16 3.75	2.25	2.70	1.00	0.75	2.60	1.85	0.45	2.08	2.05	X[i],14	III,10	13+i
6.30 4.00	2.30	2.70	1.00	0.70	2.70	2.00	0.60	1.90	1.90	XI,14	III,10	14+i
7.50 4.40	2.80	2.90	1.10	0.80	3.20	2.20	1.00	2.05	2.15	XI,14	III,10	18