1968] 
Roth & Cohen — Chromosomes of Pycnoscelus 
59 
Table 4. Classification of the chromosomes of the Pycnoscelus complex. 
Source 
Modal 
Numbers 
of 
Number a of: 
Figures 
Chromo- 
somes 
Median 
Sub- 
median 
Sub- 
terminal 
P. indicus (Hawaii) 
$ 
37 
22 
14 
1 
2 
$ 
38 
22 
14 
2 
4, 19 
35 
20 
14 
1 
1 
$ 
36 
20 
14 
2 
3, 18 
P. surinamensis 
Thailand (Pak Thong Chai 
County, Sakaerat District) $ 
33 
20 
12 
1 
7, 23 
Brazil (Serra Tamendaui) $ 
34 
20 
12 
2 
9, 20 
Australia $ 
34 
20 
12 
2 
5, 22 
Thailand (Pak Thong Chai 
County) $ 
35 
20 
13 
2 
10, 21 
Indonesia (Bogor) $ 
37 
20 
17 
0 
11, 25 
Florida $ 
53 
36 
16 
1 
13, 26 
Brazil (Belem) $ 
53 
36 
16 
1 
15 
Panama (Changuinola) $ 
54 
28 
24 
2 
16, 24 
Jamaica $ 
54 
28 
24 
2 
17 
a Terminology after Levan et al. (1965). Other nomenclature systems refer 
to the 3 classes of chromosomes as metacentric (= median), submetacen- 
tric (= submedian), and acrocentric (— subterminal). 
2n = 38 stock. It is possible that the missing chromosomes may have 
been incorporated into other chromosome sets by translocation. The 2 
forms with 53 and 54 chromosomes are of interest because they ap- 
parently differ markedly in their chromosomal morphology. It is 
likely that these arose from parthenogenetic females rather than a 
diploid bisexual stock. Females with 53 chromosomes (Florida and 
Belem) apparently have one less subterminal than those with 54 
chromosomes (Panama and Jamaica). However, they differ marked- 
ly in that the Floridian and Brazilian females have 8 more medians 
and 8 less submedians than the Panamanian and Jamaican forms. 
This suggests that the 2 clones probably arose independently from 
different stocks; i.e., clones with 53 chromosomes did not necessarily 
arise from a form with 54 chromosomes like those found in the 
Panama and Jamaica clones, simply by a loss of one subterminal. 
The results confirm White’s suggestion (in Roth 1967) that there 
could be several thelytokous biotypes of P. surinamensis related to 
the bisexual taxon of P. indicus. P. surinamensis is polymorphic, 
cytogenetically diverse, and probably arose polyphyletically by poly- 
