Kaala subrutila is a tropical land snail endemic to Mt. Kaala, Hawaii (found above approximately 3000 ft in elevation). This terrestrial gastropod mollusc is in the family Helicarionidae. This species was originally described in 1845 as Helix subrutila by Mighels. Based on morphometrics and anatomical studies, Baker described a new genus, Kaala, attributing the name to Cooke.
BAKER, H. B. 1940. Zonitid snails from Pacific islands, Part 2. Bull. Bernice P. Bishop Mus. 165: 161-163.
Unknown. Kaala subrutila, may be assessed for candidate species listing in the near future.
Specific management directed toward all native land snails should include:
- Surveys to determine the geographic ranges of all extant species.
- Systematic surveys of all extant populations to determine abundance.
- Systematic surveys to locate unknown populations.
- Conservation of remaining native forests from further loss and/or degradation.
- Control predators.
- Loss and degradation of habitat
- Non-native invasive predators (e.g. rodents, Euglandina rosea, Oxychilus alliarius)
- Insufficient information for species assessments.
Primarily a litter-dwelling species. However, this species has been found on low-lying shrubs (e.g. Broussaisia arguta, Melicope clusiifolia).
May be confused with Philonesia spp. and Oxychilus alliarus. These species belong in the family Helicarionidae and found in the same areas as Kaala subrutila.
Baker (1940) noted that the shell is solid with a domical spire, distinctly angulate on the third whorl, weakly on the fourth, and scarcely on the fifth. The base is rounded with a deep, moderately wide foveola. Coloration is amber from the top whorls, becoming lighter and more greenish below and on the fifth whorl. The shell is polished and translucent. Embryonic whorls (2 1/8 to 2 1/8) assume fine and faint spiral striae which are often partially erased in old shells. Later whorls are fairly sharp with closely spaced growth-lines and wake striae. The bases of these whorls have weaker spirals and sutures are moderately impressed. The aperture is moderately depressed but is rounded at the periphery. The peristome is about 10° to the shell-axis and concave below. The columella is truncated by a sharp, short, spiral lamella at 2.5 whorls. At 3.2 whorls, there is a heavier and more rounded cord. At 4.5 whorls, evenly thickened and rounded but noticeably obliquely truncated.
Anatomical features (Baker 1940)
Kaala subrutila is similar to Philonesa baldwini. The head, tail, and foot is dark, especially below and between the pedal grooves. The right shell-lobe is dark externally and long and triangular, about 4-5 times as long as the base. There is no left shell-lobe. The mantle lobes are dark with the left lobe deeply bipartite. The lung has a black coloration, particularly behind the mantle collar. The edges of organs are almost colorless with several white spots of various sizes. The hermaphroditic duct and post-uterine oviduct are moderately long. This species is ovoviviparous. The penial sheath includes half of the epiphalus and the corona is about as broad and long as the penis proper but over a third larger. The penial retractor occurs near the right side of the uterus and inserts just below the center of the epiphallus. The penis proper, about the size of the prostate, is short and stout with irregular internal folds. The penial prepus, about the size of the penis proper, is greatly swollen with thickened walls on the left size but without a diverticulum or sac. The atrium proper is short and opens near the base of the right inferior tentacle. Jaws are quite low and rounded but have a distinct median lobe with sharp longitudinal and growth striations. The radula has a slightly elongate central, nine laterals with small entocone lost from the last, and 45 marginals of which 0-2 are strictly bicuspid about 22 are tricuspid. 104 rows were counted.
Its most distinctive feature is the large penial prepuce, compared to the size of the penis proper, which is similar to that of Lamprocystis.
Measurements are based on specimen BBM 36606 by Baker (1940):
Altitude (greatest length parallel to the shell-axis: 6.3 mm
Major diameter (maximum width at right angles to that axis): 10.63 mm
Minor diameter (90° to the major): 10.25 mm
Altitude of the aperture (parallel to the shell-axis on a vertical plane): 4.09 mm
Diameter of aperture: 5.26 mm
Number of whorls: 4.6
Comparative whorl sizes: 1.5 wh. = 2.69 mm; 3.5 wh. = 7.8 mm; 4 wh. = 9.05 mm; 4.5 wh. = 10.38; 5 wh. = 11.8 mm.
Currently there are no published genetic data on this species. The genus Kaala, of which K. subrutila is the only known species, has a shell that would place it in Hiona. However, the soft body is similar to that of Philonesia (particularly the radula; Baker 1940).
Kaala subrutila is a tropical land snail endemic to Mt. Kaala, Hawaii (found above approximately 3000 ft in elevation). Mount Kaala is the highest peak on the island of Oahu at 4,025 feet (1,227 m) and is a part of the Waianae Range, which is located on the west side of the island. The summit of Mt. Kaala has been designated as a Natural Area Reserve in 1981.
- Found above 3,000 ft. in elevation
- Primarily epigeic
Epigeic (lives iin the surface litter and feeds on decaying organic matter)