Setal morphology of the grooming appendages of Macrobrachium rosenbergii (Crustacea: Decapoda: Caridea: Palaemonidae) and review of decapod setal classification

Abstract

Setae are vital in grooming activities and aiding in the removal of epibionts and sedimentary fouling from the body surfaces of decapod crustaceans. Thus, the setal structures and their arrangement on the grooming appendages and sensory structures of the commercially important shrimp, Macrobrachium rosenbergii, were examined using scanning electron microscopy. Macrobrachium rosenbergii is extensively grown in aquaculture and exhibits unique male morphological forms, termed morphotypes. The three male morphotypes are termed blue-clawed males, orange-clawed males, and small-clawed or undifferentiated males and all three differ in their dominance, behavior, body morphology, and reproductive success. Seven setal types, two of which have never been described in the literature, are identified on the grooming appendages (third maxillipeds, first, second, and fifth pereopods) and antennae: simple, serrate, serrulate, spiniform, pappose, crinoid, and spinulate. The latter two setae are newly identified. Certain setal types, such as serrate and serrulate setae were located and associated with specific grooming appendages such as the first pereopods. The types of setae on the grooming appendages varied among females and male morphotypes and the novel setal types (crinoid and spinulate) were found only on two of the male morphotypes. A literature review of terminology related to the structure of setae and setal types in decapod crustaceans is offered as the usage of various terms is ambiguous and conflicting in the literature. The intention of this review is to provide future authors with a comprehensive collection of terms and images that can be used to describe various aspects of setal morphology in decapods.

Setal morphology of grooming appendages in the spider crab, Libinia dubia

“…Feathered serrate setae, toothed serrate setae, and overlapping‐toothed serrate setae have larger denticules and are predicted to handle larger volumes of fouling than fringed serrate setae and stubbed serrate setae. The sturdy denticules of most serrate setae may function similarly to a large paddle hair brush, which functions to detangle large amounts of hair in humans and likely filamentous algae in crustaceans (Wortham et al, ). Serrate setae may likely detangle much fouling from the body and allow structures involved in sensory function, respiration, decoration, and movement to perform more efficiently.…”

“…Pappose setae has very fine setules and likely are too delicate to handle large amounts of fouling. Because these pappose setae are often matted on their respective appendages, their function is thought to be for fine‐detailed grooming on a smaller scale (Wortham et al, ). All five types of pappose setae are seen throughout the joints of the P1, which is a significant occurrence to see a high density of different forms of the same setal type in the same area.…”

“…Descriptions are in order starting at the ventral view and ending with the dorsal view as well as starting with distal segments on appendages and ending with proximal segments. Setae identification is based on documentation from Factor (), Pohle and Telford (), Pohle (), Watling (), Garm (), Short (), Keiler and Richter (), VanMaurik and Wortham (), and Wortham et al ().…”

“…While many studies have been conducted on the grooming morphology of other crustaceans (Bauer, ; Felgenhauer, ; Felgenhauer and Schram, ; Holmquist, ; Wortham and Van Maurik, , ), no comprehensive study exists that documents the morphologies of external and internal grooming appendages in crabs. The objective of this study is to identify setal structures correlated with grooming appendages in L. dubia .…”

Microbial proliferation on gill structures of juvenile European lobster (Homarus gammarus) during a moult cycle

“…The terminology used throughout this paper to classify, describe and identify H. gammarus setal morphology is based on a review of the decapod setal classification system by Wortham et al (2014), with particular attention to Jacques (1989), Watling (1989) and Garm (2004). All microbial counts from each animal (9 grids) were added together, and total microbial density (number/lm 2 ) was calculated as the total number of microbes divided by the total area sampled (i.e.…”