Table 1.
Developmental staging table for P. vitticeps based on Sanger et al. [40] staging system for Anolis lizards
| Stage | Description |
|---|---|
| 1. Late pre-limb bud |
Limbs: Not yet present Cranial: The neural tube is open, extending to the cranial margin of the metencephalon. The mesencephalon forms a conspicuous bulge, with little definition between it and the metencephalon Eye: Optic cups are visible as round transparent protuberances with open choroid fissures Thorax: The heart is present as a single, folded transparent endocardial tube enclosed within a membrane. Four pharyngeal clefts are open. The mesonephros is present, as are the otic vesicles Somites: Approximately 35 somites are present with no obvious tail bud |
| 2. Forelimb bud |
Limbs: The forelimb buds are present. The hindlimbs are beginning to form as slight thickening of the mesoderm close to the caudal terminus of the embryo Cranial: The neural tube remains open, extending to the caudal margin of the mesencephalon. Early meso-metencephalic constriction is apparent, and the metencephalon and mesencephalon become more distinct. The diencephalon becomes more prominent. The olfactory placodes are visible Eye: The choroid fissure is obviously narrower, while the lens and optic cups become more defined and very faintly pigmented Thorax: Three pharyngeal clefts are open. The mesonephros is larger, extending behind the presumptive liver, which has also increased in size from the previous stage. The margins of the otic vesicles become more defined. The tail bud begins to form Somites: Have increased in number from the previous stage (approximately 46), extending past the thickening hindlimb mesoderm, but terminating before the tail bud |
| 3. Hindlimb bud |
Limbs: Both the fore and hindlimbs are becoming increasingly defined and are beginning to separate from the mesoderm. All limbs are approximately the same size Cranial: Meso- and metencephalic constriction increases, giving the mesencephalon a more rounded appearance, and causing the metencephalon to appear more protuberant. The diencephalon becomes more apparent Eye: The choroid fissure remains open, and the lens and optic cup become more distinct as pigmentation darkens on the lens Thorax: Two pharyngeal clefts are open. All organs increase in size. The mesonephros extends higher in the body cavity. The endocardial tube (presumptive heart) constricts. The tail lengthens and begins to curl Somites: Continue to increase in number as they are present past the hindlimb bud and into the developing tail (approximately 48) |
| 4. Early limb bud |
Limbs: Hind and forelimb buds are well defined and approximately the same size Cranial: The margins of the mesencephalon are well defined, creating an obvious division between it and the metencephalon. The diencephalon increases in size. The neural tube narrows Eye: Little change from previous stage Thorax: All organs, aside from the embryonic kidney, are developing outside of the body cavity, but are beginning to become more enclosed within developing mesoderm |
| 5. Late limb bud |
Limbs: Both the hind and forelimb buds have increased in size and begin to show a slight pinching between the length of the limb and the developing hand Cranial: The mesencephalon continues to develop as a large, translucent protuberance. The metencephalon reduces, while the diencephalon continues to increase in size Eye: The eyes have become much larger and protuberant, taking on a uniform light brown colouration with diffuse black pigmentation surrounding the developing pupil Thorax: The heart is internalised, while the intestines remain herniated Genitalia: The cloaca begins to form as a small indentation between the hindlimb buds |
| 6. Paddle-shaped limb bud |
Limbs: Both the hind and forelimbs have a distinct paddle, or spade-like shape, but no delineated phalanges Cranial: The mesencephalon becomes slightly less protuberant and translucent, while the diencephalon becomes less translucent and moves towards the mesencephalon Eye: The eyes continue to increase in size, while the black pigmentation around the pupil becomes less diffuse Thorax: The intestines are almost completely enclosed within the body cavity Genitalia: The cloaca continues to become more defined as very small genital swellings begin to form on either side of the cloacal opening, between the hindlimbs |
| 7. Digital plate |
Limbs: Both the hind and forelimbs have become obviously proximodistally segmented, increase in width and become slightly pointed at the apex. Faint digit condensations are visible Cranial: The mesencephalon reduces further and becomes less translucent. There is also some definition of the presumptive paired brain swellings as the diencephalon continues to move towards the mesencephalon Eye: The eyes become more protuberant and the eyelid begins to form as a thin, translucent covering of skin around the ventral margin of the eye Thorax: All organs have become completely internalised Genitalia: The genital swellings increase in size and the anterior and posterior cloacal lips start to develop |
| 8. Digital condensations |
Limbs: The phalangeal bones have condensed, the interdigital webbing becomes slightly reduced, and the limb joints are more distinct Cranial: The mesencephalic lobes become more obviously delineated Eye: The overall appearance of the eye remains unchanged from the previous stage, but the eyelids continue to envelop more of the eye Genitalia: The genital swellings increase in size and start to take on a slightly club-like shape. The anterior and posterior cloacal lips continue to become more defined |
| 9. Early digital web reduction |
Limbs: The interdigital webbing continues to reduce so that the distal tips are freed, while the elbow joint becomes more distinct, making the limbs flex at approximately 90 degrees Cranial: Four mesencephalic lobes have become delineated, and the pineal eye is visible. The two posterior lobes are slightly more protuberant than the two anterior lobes Eye: The eyelid now covers approximately three-quarters of the eye Scales: Epidermal papillae first become visible, particularly along the dorsal surface Genitalia: The genitalia continue to grow and develop an increasingly club-like shape, and the cloacal lips continue to thicken |
| 10. Digital webbing partially reduced |
Limbs: The digital webbing continues to reduce to approximately half the length of the phalanges Scales: Epidermal papillae develop along the dorsal surface and margin of the presumptive beard. The epaulettes also start to form Genitalia: The genitalia now have a club-shaped appearance, but are not yet bilobed |
| 11. Digital webbing completely reduced |
Limbs: The phalanges are no longer joined by any interdigital webbing, and there is a slight pinching at the distal tips of each phalange Cranial: The posterior mesencephalic bulges become more protuberant Eye: The eyelid thickens, creating an almond-like shape around the eye. The pigmentation darkens, and the black pigmentation condenses around the pupil Scales: The epidermal papillae become more prominent along the dorsal surface and margins of the presumptive beard. Very faint pigmentation is visible on the developing epaulettes Genitalia: Both sexes now exhibit bilobed hemipenes |
| 12. Eyelid margin (digital pad) |
Limbs: The phalanges become more elongated with some joint definition and increased pinching at the distal tips, but the claws remain transparent Eye: They eyelid now covers the eye up to around the margins of the black pigmentation around the pupil Scales: Scale anlagen are present along the margins of beard and side of body, and dorsal surface. Some epidermal papillae develop on the dorsal surface along with faint, scattered pigmentation on the developing epaulettes Genitalia: Bilobed hemipenes continue to develop in both sexes |
| 13. Dorsal patterning (toe lamellae) |
Limbs: The claws are well defined and are no longer transparent. All limb joints become well defined Eye: The eyelid surrounds the pupil and beings to thicken at its anterior margins, but remains transparent, underneath which the eyes’ darkening pigmentation is still visible Scales: Epidermal papillae are now evident across the entire body. Scale anlagen increase in number and become more defined along the beard margins, sides of body and dorsal surface. Very faint, scattered melanophores appear on the developing epaulettes, extending caudally from the margins of the eye and ear hole. Patterning develops along the dorsal surface and the pigmentation slightly darkens Genitalia: Bilobed hemipenes continue to develop; however, in some females they begin to reduce in length but retain their bilobed appearance |
| 14. Mesencephalic bulge reduction (scale anlagen) |
Limbs: The limbs no longer change in shape Cranial: The mesencephalic bulges begin to reduce, and the area of the presumptive parietal bone becomes less translucent Eye: The anterior margins of the eyelid continue to thicken Scales and Pigmentation: Scale anlagen now cover most of the body, and light pigmentation appears on limbs, tail and cranium, while the dorsal patterning continues to slightly darken Genitalia: The hemipenes continue to regress in females and remain unchanged in males |
| 15. Full dorsal scales (first full scales) |
Cranial: The mesencephalic lobes continue to reduce so that the head has an even dome shape in profile. The presumptive parietal bones continue to develop, further reducing the transparency of the skull Eye: The eyelids’ anterior margins thicken further, more closely enclosing the pupil, but remains transparent. The whole eye darkens so there is no delineation between pigmentation around the pupil and the rest of the eye Scales and Pigmentation: Pigmentation has darkened considerably from pervious stage, and distinct patterns cover the entire dorsal surface. The claws also darken. Overlapping scales cover most of the dorsal surface, including the tail and limbs. Presumptive spines develop along the beard and sides of body Genitalia: In females, the genitalia continue to regress so that either the bilobed appearance is retained, or has disappeared so that the genitalia resemble small, even swellings characteristic of hemiclitores |
| 16. Fully developed scales |
Cranial: The parietal bone continues to develop so that the mesencephalic lobes are less visible Eye: The eyelids continue to thicken over the whole eye and have a well-defined almond shape around the pupil Scales and Pigmentation: Fully developed scales are now common across the body, particularly along the beard and dorsal surface. Scales begin to become more prominent on the phalanges and eyelids. Pigmentation continues to darken over the whole body, so that distinct patterns are now obvious Genitalia: In females, the genitalia generally continue to regress to hemiclitores, however, there are still some specimens that retain bilobed hemipenes or regressed hemipenes |
| 17. Eye reduction (pigmentation) |
Cranial: The parietal bone is well developed so that the cranium has a smooth dome-like appearance in profile and the mesencephalic lobes are barely visible Eye: The eyes become less protuberant, but the pigmentation and eyelid morphology remains unchanged Scales and Pigmentation: Scales continue to develop across the body and are now commonly found to be overlapping. Pigmentation darkens across all dorsal surfaces Genitalia: Most female specimens now exhibit either regressed hemipenes or hemiclitores |
| 18. Near-hatching |
Cranial: The partial bone has formed and is now covered in scales and darkly pigmented. The pineal eye is still visible Eye: The eyes are significantly less protuberant, but there is still some dark pigmentation visible under the eyelid Scales and Pigmentation: The scales are almost completely developed, and the pigmentation patterns look much like those seen in hatchlings Genitalia: The genitalia have completely regressed in females so that only the genital ridge is present within the vent. Males possess large bilobed hemipenes |
More detail is provided for morphological traits that are not described for Anolis, as well as a general characterisation of genital development. Where applicable, stages that were named after diagnostic characters in Anolis that are not present in P. vitticeps, were renamed with the original name in brackets