Review of the genus Monotheca (Hydrozoa: Leptolida) from Australia with description of a new species and a note on 
Monothecella Stechow, 1923 
85 
Figure 5. A-G, Monotheca spinulosa. A, part of stem; B, hydrocladium with short terminal spine; C, hydrocladium with long terminal spine; D, 
female gonotheca with ova; E, two views of twin lateral nematothecae; F, axillar nematotheca; G, median inferior nematotheca. Scale bar: A, 0.3 
mm; B, C, 0.2 mm; D,1 mm; E-H, 0.1 mm. 
transverse to slightly oblique, deeply constricted, an internal 
transverse septum below node. 
Hydrocladia alternate, distal on internode, in one plane, 
borne on an upwardly directed apophysis, abcauline wall of 
apophysis a smooth extension of internode, distal node a deep 
transverse shoulder with internal septum behind node, a 
minute mound-shaped hydrostatic pore in axil beside a 
nematotheca. Hydrocladium with a short proximal athecate 
internode, distal node transverse, deeply constricted with an 
internal septum, occasionally an identical secondary athecate 
internode between the athecate and hydrothecate internode. 
Hydrothecate internode narrow, short, ending in a distal spine 
of variable length, projecting beyond hydrotheca. 
Hydrotheca occupying most of internode; internode 
expanding distally as a prehydrothecal chamber between node 
and floor of hydrotheca, often a minute septum projecting 
backwards into chamber from floor of hydrotheca. Hydrotheca 
bonnet shaped, laterally compressed, adcauline wall rounded, 
set deep in internode, abcauline wall curved, proximally 
convex, straightening towards margin; margin delicate, deeply 
divided by a long V-shaped septum passing deeply backwards 
into hydrotheca, a minute triangular in septum in base of some 
hydrothecae. Hydranth with 12-14 tentacles. 
Nematothecae bithalamic, moveable, all approximately of 
same size: one cauline, halfway along internode on opposite 
side to apophysis, one on internode in axil, one median 
inferior, base close to internode, twin laterals standing erect in 
front of hydrotheca, one at each side of distal spine, bases 
short, slightly inflated, cup deeply adcaudally excavated into a 
butterfly shape. 
