Table 1.
Abbreviation and nomenclature applied in the morphological analysis.
Descriptions of landmarks and semi-landmarks used to obtain linear dimensions, curve lengths, and areas of appendages.
Fig 1.
Illustration with landmark positions used to characterize length of the four reference limbs used to characterize soft-part body size, here represented by C. salebrosa.
A) 3rd walking leg, B) mandibular, C) 1st antenna, D) 2nd antenna. Abbreviations follow Table 1.
Fig 2.
Illustration with landmark positions (red dots and white arrow for linear length) and semi-landmarks (dotted lines for curve length and grey solid line for area) on male Cyprideis sexual structures.
A–F) 1st walking leg (1WL), where the right side is indicated as transformed. C) Landmark positions and abbreviations as used in Table 1. G–I) Hemipenis. H) Indication of both units of the Cyprideis hemipenis, with terminology for specific components following Table 1. I) Landmark positions and abbreviations as used in Table 1. Left panel–C. mexicana. Middle panel–C. salebrosa. Right panel–C. torosa. Structures lost during specimen preparation indicated with grey dotted lines.
Fig 3.
Valve shape by size sexual dimorphism.
Valve shape (log[L/H]) and size (log[area]), expressed as deviations from the mean of each species female population. Deviations from the origin in the horizontal and vertical direction represent magnitudes of size and shape dimorphism, respectively. Black boxes indicate four extreme specimens of C. torosa shown in Fig 4. M = male specimen, F = female specimen.
Table 2.
Mean (m, in μm for linear dimensions, μm2 for area), coefficient of variation (CV) and sample size for the left (L) valve length, height and area, and bilateral dimorphism (L-R), with 95% confidence intervals (CI), in male and female Cyprideis.
Entries with p < 0.05 indicated in bold.
Table 3.
Mean (m, in μm), coefficient of variation (CV) and sample size for left (L) limb of each reference character and directional asymmetry (DA, L-R), with 95% confidence intervals (CI), in male and female Cyprideis.
Four non-sexually dimorphic characters were selected in female (F) and male (M) Cyprideis: 1st and 2nd antenna, mandibula and 3rd walking leg (A1, A2, Md, WL3, respectively). Nomenclature following Table 1; entries with p < 0.05 indicated in bold.
Table 4.
Mean (m, in μm for linear dimensions, μm2 for area), coefficient of variation (CV) and sample size (N) of the size of male primary sexual trait and directional asymmetry (L-R), with 95% confidence intervals (CI), and directional asymmetry (DA) of the 1WL with 95% confidence intervals in male Cyprideis.
The length of the Basal capsule distal chitinized support (HemiBCd L) and Copulatory process (HemiTE L), and area of the Terminal extension section (HemiTE A) for the left (L) side are reported. Bilateral dimorphism of the 1WL length (WL1 L; calculated as L-R) and width (WL1 W, calculated by subtracting L (Length curve—length straight line) from R (Length curve—length straight line)) is indicated to best illustrate degree of sexual dimorphism in the secondary sexual character. Abbreviations follow Table 1; entries with p < 0.05 indicated in bold.
Fig 4.
Left valves and outlines representing extremes in size and shape for male Cyprideis torosa.
(A) From left to right, most elongate male, least elongate male, and their overlain outlines. (B) From left to right, the largest male, the smallest male, and their overlain outlines.
Table 5.
Static allometry of the reference limbs lengths and distinct measurements of the sexual characters using valve area as a proxy for body size.
References limbs: 1st and 2nd antenna, mandibula and 3rd walking leg (A1, A2, Md, WL3, respectively); primary sexual traits: Basal Capsule distal chitinous support length, Copulatory complex length and Terminal Extension area (HemiBCd L, HemiTE L, HemiTE A, respectively). Abbreviations follow Table 1; p-value: n.s. p > 0.05, *p < 0.05, ** p < 0.01.
Fig 5.
Evolutionary (evol) and static (sta) allometry of the variables representing size in the hemipenis and valve area, used as a proxy for body size.
The basal capsule is represented by the Basal Capsule dorsal chitinous support length (HemiBCd L, upper panel); the terminal extension is represented by the Copulatory process length (Hemi TE L, middle panel), and the Terminal extension area (HemiTE A, lower panel). Abbreviations follow Table 1.
Fig 6.
Selected male trait—Valve relationships.
Shown are partial correlations between valve size (log[area]) and shape (log[Length/Height]) and male sexual traits, accounting for their shared relationship to softpart size. Residuals are from regressions of each variable on softpart size, as explained in the text. The terminal extension is represented by the Terminal extension area (HemiTE A, upper panel); the basal capsule is represented by the average obtained for the three lengths taken (HemiBC, middle panel); and the first walking leg is represented by the width difference between left and right side (1WL W, lower panel). Abbreviations follow Table 1.
Table 6.
Male trait—Valve relationships.
Shown are partial correlations between valve size (log[area]) and shape (log[Length/Height]) and male sexual traits, accounting for their shared relationship to softpart size. The primary sexual trait is represented by the Basal Capsule size, and the Copulatory complex length and Terminal extension area (HemiBC, HemiTE L, HemiTE A, respectively) and the first walking leg is represented by the width and curvature difference between left and right side (1WL W and 1WL L, respectably). Abbreviations follow Table 1; entries with p < 0.05 indicated in bold.