Morphometric analyses of the manus skeleton have proven useful in understanding species limits and morphological divergence among tupaiid treeshrews (Scandentia: Tupaiidae). Specimens in these studies are typically limited to mature individuals with fully erupted permanent dentition, which eliminates potentially confounding variation attributable to age, but also can exclude rare taxa and small island populations that are poorly represented in systematic collections. To determine the real limits associated with including immature animals in such studies, we used multivariate analyses to study sexual and age variation of the manus skeleton in two allopatric populations of the Lesser Treeshrew (Tupaia minor Günther, 1876) from the Malay Peninsula and from Borneo that we treated as separate samples. Individuals were aged using dental eruption of the permanent dentition. We also recorded the degree of epiphyseal fusion of the bones of the manus based on x-rays of study skins. We then tested our ability to distinguish the two populations using a series of discriminant function analyses of hand measurements from samples that included varying proportions of immature individuals and adults. We found no evidence of sexual dimorphism in hand proportions, permitting us to combine females and males in our samples. Epiphyseal fusion of the metacarpals and phalanges typically occurs by the time the third molars have completely erupted, and fusion of the distal epiphyses of the radius and ulna typically occurs by the time the permanent fourth premolars are in place. There is occasional asynchrony between dental age and epiphyseal fusion. In both populations, the hands of most infants and subadults provide morphometric values within the range of variation of adults, although they are typically distributed in the lower part of the adult range and have the potential to bias the sample toward lower mean size. The inclusion of infants and subadults when attempting to discriminate between two taxa generally results in lower rates of correct classifications, although the rates increase as the sample of immature individuals is limited to older subadults. As a general rule, we recommend that specimens of infants and subadults continue to be excluded from analyses when exploring taxonomic boundaries among treeshrews. In cases of extremely small sample sizes of adults, however, older subadults—in which the permanent third premolars are erupting or in place—can be used with appropriate caution.

中文翻译：

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成年：幼年和成年小树鼩手骨的形态变化（Scandentia：Tupaiidae：Tupaia minor Günther，1876）

马努斯骨骼的形态测量分析已被证明有助于了解 tupaiid 树鼩（Scandentia：Tupaiidae）之间的物种限制和形态差异。这些研究中的标本通常仅限于具有完全萌出恒牙列的成熟个体，这消除了可归因于年龄的潜在混杂变异，但也可以排除在系统收藏中代表性不足的稀有分类群和小岛屿种群。为了确定在此类研究中包括未成熟动物的实际限制，我们使用多变量分析来研究来自马来半岛和婆罗洲的小树鼩（Tupaia minor Günther，1876）的两个异域种群的手骨的性别和年龄变化我们将其视为单独的样本。使用恒牙列的牙齿萌出使个体变老。我们还根据研究皮肤的 X 射线记录了手骨骨骺融合的程度。然后，我们使用一系列手测量的判别函数分析来测试我们区分这两个群体的能力，这些样本包括不同比例的未成熟个体和成年人。我们没有发现手部比例存在性别二态性的证据，这使我们能够在我们的样本中将雌性和雄性结合起来。掌骨和指骨的骨骺融合通常发生在第三磨牙完全萌出时，桡骨和尺骨远端骨骺的融合通常发生在第四前磨牙永久就位时。牙齿年龄和骨骺融合之间偶尔会出现不同步。在这两个人群中，大多数婴儿和亚成人的手提供了成人变异范围内的形态测量值，尽管它们通常分布在成人范围的较低部分，并且有可能使样本偏向于较低的平均大小。在试图区分两个分类群时将婴儿和亚成体包括在内通常会导致正确分类率较低，尽管由于未成熟个体的样本仅限于年龄较大的亚成体，该比率会增加。作为一般规则，我们建议在探索树鼩之间的分类边界时，继续将婴儿和亚成体的标本排除在分析之外。然而，在成人样本量极小的情况下，