by Meeker Reptiles
Description
Members of the genus Strophurus are endemic to Australia and found throughout the continent with exception of mesic areas along the eastern coast and Tasmania. With 20 recognized species, this is the third most speciose gecko genus after Diplodactylus and Gehyra. These species share the presence of caudal glands that secrete a sticky, odorous substance down the dorsal region of the tail and most species exhibit brightly colored oral cavities ranging from dark blue to vivid yellow. As part of their threat display, this genus may open mouth gape and elevate their tail high above their body, similar to a scorpion. If they are unsuccessful in deterring their adversary, they may then aim and forcefully expel this viscous substance at their perceived antagonist.
Despite sharing these commonalities, Strophurus is characteristically separated into two subgroups – the spiny-tailed geckos and the jeweled/striped geckos. This separation is based upon their distinct habitat niches of occupying shrubs and trees or spinifex grasses respectively.
The spiny-tailed geckos (S. assimilis, S. ciliaris, S. intermedius, S. krisalys, S. rankini, S. spinigerus, S. strophurus, S. wellingtonae and S. williamsi), are arboreal or semi-arboreal in nature and derive their name from the presence of tubercles or elaborate spines, extending down the tail and around the eyes. S. taenicauda is the one exception to this rule. S. taenicauda lacks both spines and tubercles, but is often categorized within this subgroup.
The spiny-tails commonly inhabit arid to semi-arid woodlands and Acacia shrublands, and they are known for basking in full sunlight among small branches. Ranging in size from 2.5 to 3.5 inches (60-89mm) snout-vent length (SVL), this group includes the largest gecko of the genus, S. ciliaris. The spiny-tailed geckos tend to be greyish and silver in coloration. Dorsal pattern is variable and may include dark speckling, like granite, such as seen in S. williamsi, or the bolder spotting as exhibited by S. taenicauda. Some species exhibit dark, contrasting dorsal lines that may extend in a zigzag fashion longitudinally down the back of the gecko. S. ciliaris is often considered the most vividly colored species of this group and can undergo changes of cream to a chocolate brown based on time of day, temperature, lighting or temperament and may exhibit a highly contrasting colored tail with splotches of bright yellow to orange.
The second subgroup consists of the striped or phasmid geckos (S. horneri, S. jeanae, S. mcmillani, S. michaelseni, S. robinsoni, S. taeniatus, and S. wilsoni) and the jeweled gecko (S. elderi). These geckos are specialist species of Triodia or ‘spinifex’ grasslands and have a maximum size of 2.5 inches (40-66mm) SVL. This group lacks spines, tubercles, and pre-cloacal pores and parades a series of yellow or cream stripes on a grey or brown background that run longitudinally down the gecko, to include the tail. S. elderi is the exception to these stripes and is dark brown to charcoal grey with a scattering of white spots.
Two new species were recently described by Eric Vanderduys, S. congoo (2016) and S. trux (2017). S. congoo was described as “resembling the phasmid geckos in appearance, habitat and behavior, but was not closely related to the phasmid geckos,” and S. trux was described as being similar in appearance to S. congoo, but noticeably different in possessing a vividly colored yellow to golden eye. How these two new species will be grouped appears to still be open for debate.
Captivity and Housing
About seven of the spiny-tailed geckos are well represented in United States captive collections and we are currently working with two species, S. ciliaris and S.t. taenicauda. Being a smaller gecko, this genus can be kept in relatively simplistic enclosures to recreate their arid habitat. Individuals, pairs, or trios may be housed in a 12 x 12 x 18in (30 x 30 x 45cm) enclosure or larger. Height is much more important than floor space, and a combination of vertical and diagonal branches should be provided for this arboreal to semi-arboreal group.
These geckos have the ability to climb smooth surfaces and may rest where the enclosure walls intersect and some keepers provide textured backgrounds as additional climbing surfaces. Although they are perfectly comfortable out in the open and in plain view, these gecko species are known to occasionally hide under exfoliated bark, therefore bark slabs or another refuge may be appropriate. Some of our enclosures include dried grasses and our S. t. taenicauda can be found hiding among or behind these bunches on occasion. A layer of sand measuring ½ -1 inch (13-26mm) is used as a substrate.
Temperature and Lighting
A photoperiod is provided throughout the year with 14-hours of daylight during the summer months, which is decreased to 6-hours during the winter. A high temperature of 90°F (32°C) may be provided at the top of their enclosure with a temperature gradient down to the upper 70°s to low 80°s (25-27°C) at the bottom for self-regulation during the summer period. At night, no additional heat is provided and the night ambient temperatures may drop into the mid to upper 70°s (25°C). A UVB gradient is provided for our geckos with a 3.0 ultraviolet index reading at the highest part of the cage. The numerous branches and grasses provide shade options for self-regulation. Humidity and water is provided by lightly spraying the cage sides and branches at night twice weekly. Little to no evidence of water droplets should be present in the morning.
Diet
Spiny-tailed geckos are most active in the evening after the lights are turned off, which provides an ideal opportunity to observe their health and feed. They can be rather bold, scurrying down their branches as the cage door is opened in an effort to meet their prey as it is tossed into their enclosure. Their natural diet consists of arthropods in the wild and they actively forage at night among the branches and may occasionally traverse the ground while moving from shrub to shrub. They will readily accept most commercially available insects from crickets to cockroaches. Worms such as black soldier fly larvae or hornworms may be offered on occasion as part of a varied diet. Adults are fed gut-loaded prey three times a week, and a calcium and vitamin supplement is provided in accordance with the manufacturer’s direction.
Sexing and Breeding
Juveniles of this subgroup may generally be sexed around 6-12 months in age with the development of hemipenal bulges in males. Sexual maturity for most is around 12-18 months, but some may take upwards of 24 months. This genus has been known to breed year round under captive conditions, but in general follows a seasonal breeding pattern.
We’ve had the most success with seasonal separation of males and females, but many are successful with keeping pairs together year round. Males are removed from the female’s enclosure in late fall as ambient temperatures and photoperiod decreases. Our room temperatures are variable based on outdoor temperature fluctuations, and daytime temperatures range from the mid-70°s (24°C) to the mid-80°s (29°C). At night, no additional heat is provided and the night ambient temperature may drop as low as the mid to upper 60°s (18°C). UVB is continued during this cool down with an approximate 2.5 ultraviolet index reading due to natural bulb decay. Misting is reduced to one time per week and an occasional small, prey item may be offered to help maintain bodyweight. Prey is only offered when the temperatures are on the high end of the range to ensure proper digestion. After an 8-10 week cooling period, breeding activity will commence following an increase in food, temperature and photoperiod.
S. ciliaris and S. t. taenicauda reproduce on a consistent basis with a clutch interval of approximately 21 days. A moist nesting area (sand, sand/peat mix) such as an overturned terra cotta saucer or nest box with a hole cut in the top should be provided at ground level for the female. The nesting substrate should be about two inches (5cm) deep, and the female will typically deposit her eggs at the very bottom. Clear nesting boxes are ideal as they make for ease when locating the exact position of the eggs post-deposition. Gravid females undergo a pre-lay shed one to seven days before laying and are easily recognized by their distended abdomens. Females will enter the nesting area once the lights are out and will reemerge by morning. It is usually evident that eggs have been laid due to the displaced nesting substrate. Normally two eggs are laid at a time, but on occasion only one egg may be laid. Eggs are gently removed from the nesting area and may be incubated using a 1:1 ratio of perlite to water at a temperature of 80-84°F (27-29°C) , hatching around 60 days. Hatchlings are quite small and can be reared individually in 32oz deli cups with a modified screen lid. They are kept in the same fashion as adults and will accept small crickets, D. hydei fruit flies, and bean beetles. Babies are initially fed daily and then moved to every other day as they mature.
This genus can be quite prolific, with records of S. ciliaris laying upwards of 10 clutches per year. Therefore, it is recommended that the amount of food is reduced after about three clutches to slow the reproductive process, for the health and safety of the female. Despite this food reduction, females may still reactively lay 1-2 more clutches before winter.
The spiny-tailed geckos are a delightful genus to keep with their bold coloration and diurnal basking. They are hardy and small enough that several small groups can be kept in a relatively small space such as an apartment or bedroom. Communal keeping of a trio has proven trouble-free with no noticeable aggression or negative effects to the animals over the summer months. Their lifespan ranges from 6-10+ years in captivity and they will certainly continue to grow in popularity as more people have success with their husbandry and discover their captivating personalities.
