Lampropholis delicata (De Vis, 1888)

Common Name and Habitat Abundance

Lampropholis delicata, commonly called the delicate skink, is more abundant in suburban gardens than in nearby native bushland.

Body and Scale Characteristics

It has a moderate-sized body, a medium-length slender tail, and smooth scales.

Dorsal and Lateral Coloration

Its back and sides range from greyish-brown to rich brown, and often have both darker and paler flecks. A narrow yellowish-brown stripe is usually present along the outer edge of the back.

Stripe-Based Dimorphism

This species has two distinct forms based on the prominence of a white stripe, and this dimorphism is not strictly separated by gender.

Sexual Dimorphism

Sexual dimorphism is also present in L. delicata: males have broader, longer heads, while females have larger abdomens and overall body sizes.

Native Range and Taxonomy

The delicate skink is native to Eastern Australia and belongs to the skink subfamily Lygosominae.

Introduction History

It was accidentally introduced to the remote oceanic Lord Howe Island, located between Australia and New Zealand, in the 1980s, and was later introduced to the Hawaiian Islands. After introduction, these lizards spread rapidly across the islands.

Lord Howe Island Habitat

On Lord Howe Island specifically, they live in low-elevation vegetation communities.

Invasive Range

The species is also invasive in New Zealand, Hawaii, and Lord Howe Island.

Activity Pattern

L. delicata is a diurnal species with seasonal variation in activity, peaking between November and December.

Tail Loss Occurrence

Tail loss and subsequent regeneration occurs frequently in these lizards, and is most often observed in females and adults.

Reproductive Cycle Alignment

While the biological mechanisms of the reproductive cycle differ between male and female L. delicata, their cycles align seasonally to allow mating in late summer. Mating has only been observed in late summer, even though males have a second period of available sperm.

Male Winter Testes State

In males, testes contain very few mature sperm during late autumn and winter. During this period, spermatogonia are the dominant germ cells, and seminiferous tubules are at their smallest diameter.

Spring Spermatogenesis

Spermatogenesis begins in early spring, allowing development of primary and secondary spermatocytes. By the end of September, mature sperm fill the now-expanded seminiferous tubules, and sperm are depleted through October and November.

Summer Spermatogenesis

A second wave of spermatogenesis occurs in summer, producing more mature sperm by February, which are then depleted from the seminiferous tubules, first in spring and again in autumn, presumably for mating.

Female Winter Ovarian State

In females, ovaries are quiescent between February and July (autumn and winter).

Follicle Growth Period

Follicles begin growing to notable sizes between August and October (late winter and spring).

Ovulation Process

In October or November, one to two follicles per ovary become vitellogenic and are ovulated. After ovulation, the corpus luteum forms and persists until oviposition, which occurs roughly one month later.

Post-Ovulation Follicle Development

Following ovulation, many other growing follicles become vitellogenic, but they may not ovulate and can regress after the late summer mating period. All these ovarian events correspond to changes in ovarian weight.

Juvenile Reproductive Differences

While young adult females rarely have growing oocytes, young adult males of all ages undergo spermatogenesis.

Clutch Frequency

Most L. delicata produce no more than one clutch per season, but some evidence indicates young females may produce a clutch in the season after they are born, which matches males' ability to mate in both spring and late summer.

Reproductive Cycle Triggers

Although temperature and photoperiod have been hypothesized to trigger reproductive activity in these lizards, more evidence points to rainfall patterns influencing their reproductive cycles.

Low Rainfall Resource Scarcity

When annual rainfall, annual vegetation productivity, and arthropod availability are low, food becomes scarce for the lizards.

Rainfall Impact on Reproduction

This scarcity can influence follicular development in females, particularly the vitellogenesis cycle, but lower rainfall does not appear to be enough to change male testicular patterns.

Female Breeding Period

Female reproduction occurs between September and February, spanning spring to late summer.

Clutch Size Correlates

There is a positive correlation between female body size and clutch size. Clutch size most commonly varies between 1 and 7 eggs, with an average clutch size of 2 to 4 eggs (mean 3.4).

Communal Egg Nests

Communal egg nests are common, and can hold anywhere from 11 to over 200 eggs. A single clutch per year of around two to four eggs is typical for the species.