PORE PATTERN: A POSSIBLE INDICATOR OF TUBE-BUILDING IN STENHELIA AND PSEUDOSTENHELIA (COPEPODA: HARPACTICOIDA)

Abstract

ABSTRACT Tube-dwelling has been recognized as a life-style for two closely related meiobenthic harpacticoid species. Ecologists and systematic biologists may wish to know if other meiobenthic copepods build tubes, but behavioral observation of living specimens is not always possible. We report here on the results of scanning electron microscopy comparing cuticular pore patterns of known tube-builders with nontube-builders (pores are necessary to release sediment-building substances). Stenhelia (Delavalia) palustris and Pseudostenhelia wellsi are tubedwellers. They share paired, bilateral pore locations on the first urosomal segment, anal segment, and on each caudal ramus, with the largest pore (2-4 µm in diameter) on the anal segment. S. (D.) palustris is larger than P. wellsi and exhibits additional pores on swimming legs and urosome, and consistently larger pores in shared positions. S. (D.) bifidia does not build tubes, and has a markedly reduced pore complement, only a small, paired pore (<1 µm) on the anal segment. Two other species with unknown tube-building capabilities were examined. S. (D.) reflexa is similar to the nontube-builder, with only a single small pore (< 1 µm) on each caudal ramus, suggesting that it is unable to build tubes. S. (Stenhelia) asetosa has pores on urosomal segments 1, 2, 3, the anal segment, caudal rami, and swimming legs. Its pore pattern and sizes of pores are similar to the known tube-builders, and we speculate that S. (S.) asetosa is also a tube-dweller. Pores on urosomal segment 1, the anal segment, and the caudal rami, with the anal segment pore at least 2 µm in diameter, may prove to be good indicators of tube-building capability within Stenhelia and Pseudostenhelia.