Introduction

Mystacina tuberculata Gray is a small bat with a close, compact layer of fur which is generally frosted in appearance. The elongate head tapers conspicuously forwards to prominent nostrils. The simple ears have a long, narrow tragus. The thin flight membranes are exceptionally tough and the reduced propatagium, medial portions of the plagiopatagium, and the basal part of the uropatagium are conspicuously thickened. With the exception of the slender metacarpals and phalanges of the chiropatagium limb elements are robust; the feet being very large and turned outwards. The short tail penetrates the uropatagium dorsally.

This species is represented in New Zealand as two distinct forms which are here described as subspecies. One ranges throughout the North Island and is present in at least northern areas of the South Island. but the other is at present only recognised from Stewart Island and a few neighbouring islets. A specimen from Okarito, Westland, was in too poor condition to enable subspecific determination.

Historical

In 1843 Gray (in Dieffenbach, 1843a) prepared a faunal list for New Zealand. He referred, p. 181, to a bat, Vespertilio tuberculatus G. Forster of .the family Vespertilionidae, which he described as "Yellowish brown; ears small, rounded. Inhab. Dusky Bay, N.Z." In an appendix on page 296 of the same journal he stated that having received two specimens of the New Zealand bat he found it belonged to a new genus and accordingly described it as Mystacina tuberculata. He maintained this synonymy in the Catalogue of Mammalia in the British Museum (Gray, 1843b) and included the bat in the group Noctilionina.

Had Gray been able to examine Forster's Vespertilio tuberculatus he would have realised that his animal was distinct. It remained, however, for Tomes (1857) to show that there were, in fact, two New Zealand bats. Tomes included Gray's bat in the family Noctilionina describing it as Mystacina tuberculata Gray. Later Tomes (1863) referred Mystacina to the family Phyllostomidae but Gray (1866) again considered it with the Noctilionidae (equals Noctilionina of Tomes, 1857). Hutton (1872) indicated the confusion apparent in having equivalent trivial names for the two New Zealand bats and proposed that the name Mystacina velutina be adopted in reference to the velvet-like nature of the fur of the short-tailed bat.

Dobson (1875) considered Mystacina tuberculata to belong to the family Emballonuridae, but to differ from typical members of that family in possessing a third phalanx in the middle finger, a feature which he described for the American Phyllostomidae. He separated Mystacina as a group Mystacinae (subfamily Molossinae) of the above family.

Lydekker (in Flower and Lydekker, 1891) claimed that Mystacina Gray was preoccupied by Mystacina Boie, 1822^* and proposed instead the name Mystacops tuberculatus (Gray). His change was generally adopted. Winge (1892) referred Mystacina to the Vespertilionidae. Thomas (1905) suggested that since Gray's first reference (in Dieffenbach, 1843a) to New Zealand bats included the first published indication of Vespertilio tuberculatus this made Gray the author of that name and at once invalidated Gray's own name for the short-tailed bat. On these grounds he reinstated Hutton's name of 1872 and called the bat Mystacops velutinus (Hutton). Miller (1907) did not accept these conclusions. He retained the proposal of Lydekker and considered the bat as the sole representative of a new family, Mystacopidae. Simpson (1945) resurrected the original generic name and attributed authorship to Gray. His family Mystacinidae is equivalent to Miller's Mystacopidae.

Material Examined and Acknowledgments

Mystacina tuberculata robusta subsp. nov. (Figs. A. B, D.)

Range: Only known from the Stewart Island region, N.Z.

In contrast to the northern subspecies this animal is larger and extremely robust. page 4Total length is up to about 90 mm, wing span to about 310 mm. It has the ears falling short of the muzzle tip, and has the wide nostrils lying relatively closer against the muzzle.

Type. Male from Big South Cape Island, Dominion Museum Specimen 1083.

Mystacina tuberculata

Fig. A, M. t. robusta, dorsal. Fig. B, Head of M. t. robusta, lateral. Fig. C, Head of M. t. tuberculata, lateral. Fig., D, Head of M. t. robusta, ventral. Fig. E, Head of M. t. tuberculata, ventral.

Discussion

Table I shows the relationship of ear length (from junction with head and from meatus), forearm length, digital length (third metacarpal and associated phalanges) to total length for the eleven specimens of Mystacina available during this study. Comparable date from the literature has been included and where possible the subspecies has been indicated. "Ear length" of Hutton (1872) and Dobson (1878) has been considered equivalent to "ear length from meatus" in the present table. Carter, Hill, and Tate (1946) give measurements for the head and body, for the tail and for the forearm, but these are approximations of Dobson's (1878) values and have not been included here. Values based on ear measurements for D.M. 352 (female) are considered unreliable as the specimen was a skin in poor condition and these structures were somewhat withered.

With the exception of this last specimen the values for ear or forearm length compared with total length fall into two groups corresponding with the known ranges of the two subspecies. Ear length from junction with head as a percentage of total length is above 20% in M. t. tuberculata but below this value in M. t. robusta. The values for ear length from meatus are more distinct, above 25% in the northern subspecies, below 23.5% in M. t. robusta. For the forearm corresponding values are 62.5% and 60%. The relationship between digital length and total length is not so marked. Values for M. t. robusta are generally lower, but Knox's (1872) measurements appear to provide an overlap.

The distinction between the subspecies relates both to overall size and to the relative proportions of exposed parts such as nostrils, ears and limbs. Overall size is greater and the extremities relatively shorter in M. t. robusta than in the northern M. t. tuberculata. Such differences are in accordance with Bergmann's and Allen's page 6rules (Allee, Emerson et. al., 1949) relating to structural modifications induced by temperature. No evidence of a continuous cline along a temperature gradient is apparent from the few specimens available. It is noted by Allee, Emerson et. al., that hibernation may reduce the effect of temperature upon structure in mammals by avoiding exposure of the animals to winter minimum temperatures. It is of interest, therefore, that there is some evidence that Mystacina does not undergo a strict period of hibernation during winter months.