ACACIA CONSTRICTA (FABACEAE: MIMOSOIDEAE) AND RELATED SPECIES FROM THE SOUTHWESTERN U.S. AND MEXICO

Vegetative, fruit, and floral characters of more than 200 herbarium specimens of Acacia constricta and closely related species from the Southwestern U.S. and Mexico were scored and analyzed by principal components analysis (PCA) and stepwise discriminant analysis (SDA). The results show that all of the 5 species of this group are distinct and form nonoverlapping groups in plots of the first three principal components. All taxa were found to be quite homogeneous as indicated by the tight clusters formed in the PCA plots. Acacia pacensis, whose relationship to the species of this group has been questioned, is confirmed to be more closely related to A. farnesiana and related species. Some specimens with a combination of characters from A. constricta, A. neovernicosa, and A. schottii were positioned intermediate to the putative parental species groups in the PCA and SDA plots, suggesting hybridization among these taxa.     

EFFECT OF SOIL MOISTURE AND SIMULATED RAINFALL ON PUPAL SURVIVAL AND MOTH EMERGENCE OF HELICOVERPA PUNCTIGERA (WALLENGREN) AND H. ARMIGERA (HÜBNER) (LEPIDOPTERA: NOCTUIDAE)

Prepupae of Helicoverpa punctigera (Wallengren) and H. armigera (Hübner) were allowed to pupate in a black cracking-clay soil at different moisture levels. No differences in pupal survival and moth emergence were recorded where soil moisture ranged from dry to very wet when prepupae tunnelled into the soil. In a second experiment, simulated rainfall after pupation, but before moth emergence, reduced survival by disrupting emergence tunnels and trapping moths in their tunnels. This effect was greater where prepupae had tunnelled into dry soil than where they had tunnelled into wet soil.     

DIAPHORODENDRACEAE,FAM. NOV. (LYCOPSIDA: CARBONIFEROUS): SYSTEMATICS AND EVOLUTIONARY RELATIONSHIPS OF DIAPHORODENDRON AND SYNCHYSIDENDRON,GEN. NOV.

Synchysidendron, gen. nov., is segregated from Diaphorodendron DiMichele emend. Both genera are determinate, rhizomorphic, arborescent lycopsids that share identical reproductive organs but differ radically in growth architecture and consequently in the timing of reproduction. Cones in Synchysidendron (two species) are borne on late-formed crown branches; in Diaphorodendron (three species) cones are borne on deciduous lateral branches, produced over much of the life of the tree. The two genera also differ in several characteristics of the stele and periderm. We hypothesize that Diaphorodendron gave rise to Synchysidendron within their shared Late Carboniferous coal-swamp habitat, by heterochronic suppression of lateral branching during ontogeny. Together, these genera form a highly apomorphic clade, here recognized as the new family Diaphorodendraceae, that is distinguished primarily by siphonostelic axes, a bifacial periderm, distinctive megasporangia, and gulate megaspores.     

PSEUDO-NITZSCHIA PUNGENS AND P. MULTISENES (BACILLARIOPHYCEAE): NUCLEAR RIBOSOMAL DNAS AND SPECIES DIFFERENCES1

The region of the nuclear ribosomal DNA (rDNA) operon containing the small subunit (SSU), internal transcribed spacer 1 (ITS1), and a portion of the 5.8s rDNA gene was sequenced in one isolate each of Pseudo-nitzschia multiseries (Hasle) Hasle and Pseudo-nitzschia pungens (Grunow in Cleve & Möller) Hasle. The SSUs of these two species were highly similar, differing only in 14 point mutations and one insertion/deletion in 1774 bp. The ITS1 sequences were more variable, with 57 point mutations and three insertion/deletions in 257 bp. There were no differences in 44 bp of the 5.8S sequences. Restriction fragment patterns (RFPs) for the restriction endonucleases HaeIII, Hha1, and Rsa1 for 13 isolates of P. multiseries from the Atlantic, Pacific, and Gulf coasts of the United States and 16 isolates of P. pungens from the three coasts of the United States, in addition to Japan and China, were compared. There were differences between the RFPs of P. multiseries and P. pungens that corresponded to sites mapped by the DNA sequences, but no infraspecific variation in RFPs was observed for either species. The differences in RFPs correlate with morphological, immunological, and other rDNA differences and support the recognition of these taxa as separate species.