Bassariscus astutus (Lichtenstein, 1830)

Frederick B. Stangl, Jr., Henry-Langston, Sarah, Lamar, Nicholas & Kasper, Stephen, 2014, Sexual Dimorphism In The Ringtail (Bassariscus Astutus) From Texas, Occasional Papers of the Museum 328, pp. 1-12 : 3-10

RESULTS

Sexual dimorphism for Bassariscus astutus was pronounced ( Table 1 ). Only for postorbital breadth did females average marginally larger than males, albeit insignificantly so. For the remaining characters, males averaged larger. These differences were highly significant, with the exceptions of bullar width, dimensions of foramen magnum, and breadth of M1. Discriminant function analysis of age classes 2 and 3 served to accurately predict the sex for 95% (74 of 78) of the individuals. Misclassified specimens included two animals listed as males (MWSU 7500, TTU 17409) and two listed as females (TTU 1671, TTU 6663).

Males comprised the majority of known-sex individuals (60 of 93), and outnumbered females for each of the first three age categories. Age categories and breakdown by sex were as follows: age class 1 (n = 13): 5 males, 4 females, 4 of unknown sex; age class 2 (n = 96): 42 males, 21 females, 33 of unknown sex; age class 3 (n = 34): 12 males, 5 females, 17 of unknown sex; and age class 4 (n = 9): 1 male, 3 females, 5 of unknown sex. As noted above, there were no significant differences among each of the four age classes for either sex, although subadults generally were smaller than older aged specimens, and senile adults generally larger than younger animals.

More than half of the specimens of B. astutus initially analyzed in this study originated from the Balconian (n = 88) Province. Remaining animals were taken from the Chihuahuan (n = 40), Texan (n = 15), Kansan (n = 7), and Tamaulipan (n = 1) provinces. Samples were small for some provinces, but there was no significant geographic variation noted of either sex for any character.

TEXAS (n = 146).— Bandera Co.: 18 mi NW Medina , 1 ( TTU 92544 ). Brewster Co.: Black Gap Wildlife Area , 1 ( TTU 1381 ); BBNP, Harte Ranch Mt. Lodge, 1 (TTU 62985); 13 mi N, 3 mi W Marathon, 1 (TTU 29028); 13.4 mi N, 4 mi W Marathon, 1 (TTU 29026); 13.5 mi N, 2.5 mi W Marathon, 1 (TTU 29025); 13.75 mi N,. 75 mi W Marathon, 1 (TTU 29024); 17.3 mi N, 0.6 mi E Marathon, 1 (TTU 22980); 17.9 mi N, 0.3 mi E Marathon, 1 (TTU 22981); 18 mi N, 3.0 mi E Marathon, 1 (TTU 22982). Burnet Co.: Burnet, 1 (MWSU 21871); 1.5 mi N, 3 mi W Naruna Community, 1 (TTU 59703). Clay Co.: 20 mi S Henrietta, 1 (MWSU 11040). Comanche Co.: 6 mi S Gorman, 1.5 mi E Hwy 6, 1 (TTU 43365). Crockett Co.: 9 mi S, 5 mi E Iraan, 1 (TTU 58509). Culberson Co.: Guadalupe Mts., Lower McKittrick Canyon, 1 (TTU 25167); Guadalupe Mts., Upper Dog Canyon, 1 (TTU 32452); Sierra Diablo WMA, 1 (TTU 75781). Edwards Co.: 18 mi N Barksdale Eagles Nest Ranch, 1 (TTU 107712). Garza Co.: 16 mi S, 5 mi E Post, 2 (TTU 56563-4). Hood Co.: 4.2 mi N Granbury, 1 (MWSU 21769). Howard Co.: Big Spring, 1 (MWSU 6049). Jack Co.: 9 mi N Graford, 1 (MWSU 10946). Jeff Davis Co.: Fort Davis, 1 (MWSU 10945); 9 km N, 9.5 km E Fort Davis, 2 (TTU 32453, 32455); 9 mi NE Fort Davis, 2 (TTU 14063, 17409); 9.2 mi NE Fort Davis, 1 (TTU 17408). Kendall Co.: 2 mi N, 2 mi W Sisterdale, 1 (TTU 57961). Kerr Co.: 14 mi W Hunt, 1 (MWSU 9808). Kimble Co.: 5 mi E Junction, 1 (MWSU 7507); 6 mi E Junction, 1 (MWSU 1378); 7 mi E Junction, 17 (MWSU 1767-9, 1777, 8785, 8788-9, 8791-2, 8794, 8797, 8800-1, 8803, 8806-7, 8811); 8 mi E Junction, 14 (MWSU 6473, 6484-6, 6488, 8779-80, 8784, 8786, 8795-6, 8798-9, 8809); 10 mi E Junction, 21 (MWSU 3388, 3704, 4077, 6469, 6474, 6476-83, 7499-506); 12 mi E Junction, 8 (MWSU 8778, 8781-2, 8787, 8790, 8793, 8805, 8808); Kimble Co., no specific locality, 3 (MWSU 1374, 3387, 6475); 1.6 mi S, 3 mi W Junction, 3 (TTU 23724-23726); 5 mi W Junction, 1 (TTU 39494); Texas Tech University Center at Junction, 1 (TTU 71102); Walter Buck WMA, 1 (TTU 76655). McCulloch Co.: Near Brady, 1 (MWSU 16527). Menard Co.: 20 mi E Menard, 1 (MWSU 6050); 4 mi N, 8 mi W Menard, 1 (TTU 59704); 14 mi W, 2 mi S Menard, 1 (TTU 6661). Nolan Co.: 14 mi SE Sweetwater, 1 (TTU 6664). Palo Pinto Co.: 1 mi S Brad, 1 (MWSU 11512); 4 mi NNE Palo Pinto, 1 (MWSU 750); 10 mi W Graford, 1 (MWSU 8932); 11 mi W Graford, 1 (MWSU 13326); 15 mi W Graford, 1 (MWSU 18723); 17 mi SW Graford, Brazos River, 1 (MWSU 11513); Possum Kingdom State Fish Hatchery, 1 (MWSU 13386); Santo, 1 (MWSU 747); Possum Kingdom Lake, 2 (TTU 38698, 38699). Pecos Co.: 5 mi S, 2 mi E Girvin, 1 (TTU 49075); 12.2 mi N, 19.7 mi E Marathon, 1 (TTU 25161). Presidio Co.: 6.5 mi NW Plata, 1 (MWSU 8802); Big Bend Ranch State Natural Area, 2 (TTU 67579, 67580); Clay Miller Ranch, 2 (TTU 9755, 11770); 10 mi WSW Valentine, Clay Miller Ranch, 1 (TTU 78532); 11 mi W Valentine, 4 (TTU 92744-92746, 92764). San Saba Co.: 5 mi E Cherokee, 1 (TTU 92786); 7 mi SE Bend, 1 (TTU 92787). Stephens Co.: 4 mi E Breckenridge, 1 (MWSU 8810). Sutton Co.: 4 mi S Sonora, Hwy 1691, 1 (TTU 9756); 35 mi E Sonora, 1 (TTU 35908). Terrell Co.: 20 mi S Sheffield, 1 (TTU 92796); 23 mi S Sheffield, 1 (TTU 92801). Tom Green Co.: 2 mi S San Angelo, 1 (TTU 92810). Travis Co.: 5 mi W Austin, Gaines Ranch, 1 (TTU 92820); 6 mi SW Leander, 1 (TTU 1671B); Travis Co., no specific locality, 1 (TTU 1671A). Val Verde Co.: 3 mi W Comstock, 1 (MWSU 7839); 12 mi N Comstock, 1 (MWSU 15459); 44 mi N Del Rio, 1 (TTU 6663). Wichita Co.: 1 mi W Wichita Falls, 1 (MWSU 751). Young Co.: Young Co., no specific locality, 1 (MWSU 5986).

APPENDIX (CONT.)

MEXICO (n = 6).— Coahuila: 15 mi E Monclova, Gloria Mts., 2 (TTU 92458, 92459); 27 mi NE Muzquiz, Mariposa Ranch, 3 (TTU 92462-92464). Nuevo Leon: 1 km N San Josecita, Zaragoza, 1 (TTU 57122).

Tables

Table 1. Comparison of cranial and dental measurements (in mm) between sexes of adult (age classes 2, 3) ringtails (Bassariscus astutus flavus) from Texas. Descriptive statistics are: sample size (n), mean, standard deviation (SD), minimum and maximum measures, confidence intervals (C.I.), and coefficient of variation (CV). Probability values (P) derived from one-way ANOVAs; non-significant results indicated by n.s.

Sex (n)	Mean ± SD	Minimum-maximum	95% C. I.	CV	P
Rostral breadth
Male (54) Female (26)	14.9 ± 0.6 13.6 ± 0.8	13.6–16.3 12.6–15.5	14.7–15.1 13.2–13.9	4.2 5.8	<0.0001
Interorbital breadth
Male (54) Female (26)	16.6 ± 0.8 15.8 ± 0.8	14.8–18.5 14.7–17.6	16.4–16.8 15.5–16.2	4.7 5.4	<0.0001
Postorbital breadth
Male (54) Female (26)	17.7 ± 1.5 18.0 ± 1.7	13.5–22.0 14.3–21.5	17.3–18.1 17.3–18.7	8.3 9.6	n.s.
Zygomatic breadth
Male (53) Female (26)	50.6 ± 2.3 47.3 ± 2.4	46.3–55.5 43.0–54.6	50.0–51.2 46.4–48.3	4.4 5.2	<0.0001
Mastoid breadth
Male (53) Female (26)	36.0 ± 1.0 34.2 ± 1.0	33.8–38.0 32.3–36.7	35.7–36.2 33.8–34.6	2.8 2.9	<0.0001
Bullar length
Male (54) Female (25)	12.6 ± 0.5 12.2 ± 0.5	11.6–13.7 11.4–12.9	12.4–12.7 12.0–12.4	3.8 3.8	<0.001
Bullar width
Male (54) Female (26)	10.4 ± 0.5 10.3 ± 0.3	9.4–11.4 9.7–10.8	10.3–10.6 10.1–10.4	4.2 2.7	n.s.
Condylobasal length
Male (52) Female (26)	79.4 ± 2.2 76.2 ± 1.9	74.1–83.4 73.8–81.2	78.8–80.0 75.4–76.9	2.7 2.5	<0.0001
Foramen magnum width
Male (50) Female (26)	11.9 ± 0.6 11.6 ± 0.5	10.6–13.3 10.7–12.5	11.7–12.0 11.4–11.8	5.2 4.3	n.s.