Abstract
Background:
Accurate biotype identification in South American domestic camelids (SAC) reared in mixed herds remains a persistent challenge. Phenotypic classifications have been limited by outdated information and an over-reliance on morphological traits, leading to frequent misclassification — particularly in intermediate forms such as the Huarizo, or when considering whether the Chaku Llama biotype may represent an undefined cross with alpaca.

Aim:
To examine the relationship between fiber length and the extent of fleece coverage in SAC, and to identify potential indicators for genotype-based biotype classification in llamas and alpacas.

Methods:
A total of 2,027 SAC were sampled from high-Andean peasant communities in the southeast of the Tacna Region, Peru. The following pre-established biotypes were recorded: Huacaya Alpacas (AH, n = 1,556); Suri Alpacas (AS, n = 25); Intermediate Alpacas (AI, n = 31); Huarizos (HZ, n = 81); Chaku Llamas (LCh, n = 42); Kara Llamas (LK, n = 189); and Intermediate Llamas (LI, n = 103). Fleece coverage was assessed for the face, neck, extremities, and ears. Fiber samples were collected from the mid-side and analyzed for staple length (cm), mean fiber diameter (µm), coefficient of variation of fiber diameter (%), and prickle factor (%). ANOVA was applied to continuous variables and contingency tables to categorical data.

Results:
Staple length showed consistent and hierarchically ordered differences among all biotypes across three complementary measures (SL, SLadj., AFL), with large to very large effect sizes in most pairwise comparisons. Mean fiber diameter and prickle factor did not differ significantly among biotypes, indicating that previously reported quality differences are attributable to age-related effects rather than genetic determinism. Fleece coverage traits — particularly neck coverage — showed significant associations with staple length and demonstrated diagnostic value for biotype differentiation.

Conclusion:
Staple length and fleece coverage traits constitute reliable indicators for genotype-based biotype classification in SAC. Their combined use enables more accurate biotype identification, avoiding the misattribution of phenotypic variants to undemonstrated crossbreeding events, as frequently occurs when referring to the Chaku Llama biotype.

Key words: Biological types; Fiber coverages; Fiber length; South American domestic camelids.