natation

Abbreviations employed include the following: AD, anterodorsal; AV, anteroventral; AT, total number of sensilla on the anterior face; hrl, hair-like; PD, posterodorsal; PV, posteroventral; PT, total number of sensilla on the anterior face, excluding NS, natatory sensilla Appendage Location Coxa Femur Tibia Tarsus AD 7-8 7-8 1 1 AV 6-8 14-17 2 0-1 AT 13-16 21-25 3 1-2 Proleg PD 6-8 2-4 + 1 2-3 + 1 2-3 + 1 hrl + 1 hrl + 1 hrl + 1 PV 5-6 6-10 4-5 4-5 PT 11-14 10-16 8-9 8-10 NS 0 0 5-7 2-3 AD 7-11 15-21 7-10 1 AV 6-10 17-23 7-9 7-9 AT 13-21 32-44 14-19 8-10 Metaleg PD 6-9 3-5 + 1 hrl 1 hrl + 1 1 hrl + 1 PV 6-10 8-11 4-6 0-1 [PT.sup.1] 12-19 12-17 6-8 2-3 NS 0 0 17-23 15-24

Exopod 2-segmented, distal segment with 4 terminal plumose natatory setae.

The natatory setae, with diameters of about 2 [micro]m, experience Reynolds numbers of about 0.06 (antennulae) and 0.1 (antennae).

1G) Endites separated by shallow notch and with multiple setae; bilobed epipod; endopod 4-segmented with 6, 3, 3, 4 setae; exopod with 14 plumose natatory setae; terminal segment with 3 terminal spines and 1 subterminal spine.

Precoxae + coxae of fourth legs of males and females with posterior boot-shaped natatory lobes fringed with plumose setae and bearing scattered, coarse-pectinate scales; distal end of lobes extend beyond middle of bases but not beyond distal end of bases.

Morphological adaptations for pelagic life such as natatory exopods, which occur in all species, and lightly calcified, almost membranous exoskeleton of some genera are evidence of the habitat they occupy (Bauer, 2004).

Sympods of all legs and natatory lobes bearing plumose setae similar to those on exo- and endopods.

These appendages, however, serve a natatory function, and it is not known whether the setae play a sensory role.

Respective lengths of pro-, meso-, and metalegs, 1.64-2.02 mm ([bar.x] = 1.81 [+ or -] 0.14 mm), 1.79-2.17 mm ([bar.x] = 1.98 [+ or -] 0.13 mm), 1.81-2.54 mm ([bar.x] =2.13[+ or -]0.19 mm); natatory sensilla absent; ventral spinulae well-devetoped on protibia and protarsus, present but less well developed on remaining legs; small spinulae on surface of all segments, more numerous on protarsus; coxa robust and elongate, coxal sutures present; trochanter divided into two regions; tarsal claws sub-equal in length, anterior claw slightly longer than posterior, each with ventroproximal spinulae.

These larvae have well-developed series of natatory sensilla characteristic of nektonic dytiscids with the distribution of the spiniform sensilla corresponding to patterns of previously described larvae of Dytiscinae.

1, Tables I and II) Range of respective lengths of pro-, meso-, and metalegs, excluding trochanters and claws, 3.0 to 3.3, 3.3 to 3.5, and 3.3 to 3.4 mm; coxal sutures absent; trochanters with 7-10 sensilla, secondary homolog of T[R.sub.2] not observed; anteroventral and posterodorsal natatory sensilla present on femur, tibia, and tarsus; tarsus with anteroventral series restricted to proximal half and posterodorsal series along the length of the segment; tibia without ventral spinulae, tarsal ventral spinulae robust, present anteroventrally on distal half; posterior tarsal claw shorter than anterior and broadly spinous ventrally.

The presence of tarsal and tibial natatory sensilla and short secondary sensilla on the proximal urogomphal segment is consistent with the chaetotaxy of previously described Neoporus species.

Chaetotaxy is comparable to that of previously described Neoporus, including tarsal and tibial natatory sensilla and short secondary sensilla on the proximal urogomphal segment.