Occurrence of phoresy between Ancistrus multispinis (Actinopterygii: Siluriformes) and Ichthyocladius sp. (Diptera: Chironomidae) in Atlantic forest streams, Southeastern Brazil

Abstract

. Phoretic relationships often bring large advantages to epibionts. By attaching themselves to mobile hosts, epibionts are able to: expand their ranges without spending energy, reduce their risk of being predated, and increase their probability of finding food. We assessed the phoretic relationship between the siluriform fish Ancistrusmultispinis (Regan, 1912) and the chironomid larva Ichthyocladius sp. in three streams of the Atlantic forest in southeastern Brazil. We evaluated changes in epibiont distribution throughout the body regions of the host and among three different aquatic systems. We had predicted that certain body regions are more prone to support epibiont attachment, and that epibiont prevalence increases with increased host size and quality of the aquatic system. Three streams (Santana, São Pedro and D’Ouro), tributaries of the Guandu River, were sampled during 2010 and 2011. A total of 102 specimens of A.multispinis were collected and analyzed. Epibionts were found in fourteen of fifteen body regions of the host. Observation from scanning electron microscopy revealed that Chironomidae larvae fix themselves to the spicules through the anal prolegs, not at the skin, as previously reported. The amount of epibionts (degree of infestation) was significantly correlated with fish size in the Santana Stream (r = 0.6, p < 0.01), and São Pedro Stream (r = 0.56, p < 0.01), but not in the D’Ouro Stream, the most altered of the three. The presence of epibionts on the body of the fish is directly correlated with the availability of spicules on the fish’s body, the largest numbers of infestations being found in structures associated with swimming (caudal and pectoral fins), since the swimming movement can create favorable conditions (e.g., suspension of organic particles, increasing oxygenation) for the epibiont.

Phoretic association between Hisonotus chromodontus (Loricariidae: Hypoptopomatinae) and Ichthyocladius sp. (Diptera: Chironomidae) larvae in Amazonian streams

“…The phoresy recorded in this study represents a commensal interaction that benefits chironomid larvae (White et al 2017, Silknetter et al 2020. The findings of the present study, in which we detected only a single larva attached to each host, contrast with those of other studies that have reported means of 12.21 (Sydow et al 2008) and 13.2 (Mattos et al 2018) Ichthyocladius larvae associated with loricariid fish species. These studies have described loricariid hosts with relatively large body lengths of 104 mm (Sydow et al 2008), 93 mm (Dala-Corte & Melo 2018), and 63 mm (Mattos et al 2018), compared with the maximum length of 43 mm SL for the Hisonotus chromodontus specimens collected in the three streams we investigated.…”

“…The Ichthyocladius larvae associated with fish gain advantages with respect to diet (continuous access to debris and algae available on the host body), mobility (avoiding unfavorable habitat sites), protection against predators (larvae are camouflaged by the host) and environmental disturbance (commensal species vulnerable to environmental disturbance exploit hosts to evade areas exposed to such disturbance) (Tokeshi 1993). As observed herein, larvae prefer attachment sites in the vicinity of pectoral and pelvic fin of fish, which is presumably associated with the fact that chironomids feed on algae and debris suspended by the movement of loricariids (Henriques-Oliveira et al 2003, da Silva et al 2008, Sydow et al 2008, Mattos et al 2018. Ichthyocladius larvae have thick posterior pseudopods bearing strong claws that facilitate attachment to the host, and construct cocoons shaped like fish scales attached to the spines of host fish fins (Trivinho-Strixino 2014).…”

“…For example, the larvae of Ichthyocladius Fittkau 1974 (Chironomidae: Orthocladiinae) and others larvae midges belonging to this group have been observed in association with the siluriformes fish of families Astroblepidae, Loricariidae, and Trichomycteridae (Fittkau 1974, Pinder 1986, Mendes et al 2004, Trivinho-Strixino 2014. Loricariidae fish (armored catfish) have been described as hosts of Ichthyocladius larvae, including Ancistrus, Chaetostoma, Corumbataia, Harttia, Hemipsilichthys, Hisonotus, Hypostomus, Kronichthys, Neoplecostomus, Otothyropsis, Pareiorhaphis, and Pareiorhina (Vilella 2002, Mendes 2004, Roque et al 2004, Sydow et al 2008, Henriques-Oliveira & Nessimian 2009, Dala-Corte & Melo 2018, Mattos et al 2018. The first observations of phoretic interactions between loricariids and Ichthyocladius larvae were recorded in rivers of the Amazon basin (Freihofer & Neil 1967), whereas in Brazil, other occurrences have recorded in the south (Vilella 2002, Sydow et al 2008, Dala-Corte & Melo 2018 and southeast Atlantic watersheds (Mendes 2004, Roque et al 2004, Henriques-Oliveira & Nessimian 2009, Mattos et al 2018.…”

High cryptic diversity in a caddisfly that co-occurs in lakes and streams

“…In Quebec, Canada, Limnephilus has been documented to have water mite larvae (Hygrobatoidea), with prevalence ranging from 4-42% (Fairchild and Lewis 1987). Other aquatic organisms, like the fish Ancistrus multispinis in Atlantic forest streams in Southeastern Brazil, have chironomid larvae in phoretic association (Mattos et al 2018). Understanding the role of associated macroinvertebrates on aquatic organisms is a challenging topic to study; (Grabner 2017) found testing for parasitic taxa using PCR might be an efficient and cost-effective method to identifying links between host feeding type and prevalence.…”