2021. Journal of Arachnology 49:151–155 SHORT COMMUNICATION Paternal care in the Neotropical harvestman Cynorta bromeliacia (Opiliones: Cosmetidae). Brittany N. Damron 1,4 , Kevin O. Sagastume-Espinoza 2,4 and Stuart J. Longhorn 3,4 : 1 Departamento de Zoologia, Instituto de Bioci ˆ encias, Universidade de S ˜ ao Paulo, Caixa Postal 11461, 05422-970 S ˜ ao Paulo, SP, Brazil: Email: b.damron.15@ gmail.com; 2 Laboratorio de Zoolog´ ıa, Escuela de Biolog´ ıa-Facultad de Ciencias, Universidad Nacional Aut ´ onoma de Honduras (UNAH), Bulevar Suyapa, Tegucigalpa, Honduras; 3 Arachnology Research Association, United Kingdom (UK); 4 Operation Wallacea, Wallace House, Old Bolingbroke, Lincolnshire, PE23 4EX, UK. Abstract. We report observations over several field seasons of egg and juvenile guarding by males of a Central American species of cosmetid harvestman (Opiliones: Cosmetidae), Cynorta bromeliacia Goodnight & Goodnight, 1947. This represents only the second species of the family Cosmetidae that has been reported to exhibit paternal care. Importantly, we observed multiple instances of solitary male egg-guarding, including examples where eggs and young were at different stages of development. We also observed a few cases of mate guarding by a male at an oviposition site, where the female was near to eggs that appeared to have been recently laid. We discuss these observations in relation to the arboreal tendency of this species and speculate that oviposition sites are close to roosting sites or other such refuges for either the male or both sexes. Given the weak sexual dimorphism displayed by the species, we discuss that the externally visible characters we used to identify males are unlikely to provide any advantage in fighting off conspecific males. We also suspect that females may produce multiple clutches in this species, but this remains to be verified. Finally, we discuss how our findings at the end of the wet season may relate to the local microclimate and suggest further standardized observations throughout the year are required. Keywords: Male egg-guarding, mate guarding, reproduction, Honduras, Cusuco https://doi.org/10.1636/JoA-S-19-028 Many aspects of the biology of the arachnids are well studied, including diverse facets of their reproduction. While various degrees of maternal care are rather common for arachnids, paternal care is rare. For the latter, egg-guarding by males has only been observed in seven families of the harvestmen Order Opiliones (after Machado & Mac´ ıas-Ord ´ o˜ nez 2007; Requena et al. 2014) namely; Assamiidae (Martens 1993), Gonyleptidae (Stefanini-Jim et al. 1987; Machado & Raimundo 2001; Hara et al. 2003; Machado et al. 2004; Machado & Mac´ ıas-Ord ´ o˜ nez 2007; Nazareth & Machado 2009, 2010; Requena et al. 2009), Nomoclastidae (Rodr´ ıguez & Guerrero 1976; Mora 1990), Podoctidae (Martens 1993), Stygnidae (Villarreal & Machado 2011), Triaenonychidae (Forster 1954, see Machado 2007), and most importantly for our study, only once before for Cosmetidae (Proud et al. 2011). In the few known cases of egg-guarding in harvestmen, behavior varies depending on the sex of the caring individual (i.e., female or male). Maternal care is typically of eggs that are all of the same age, which the mother will protect from predation by shielding with her body or by actively attacking predators, as recorded in some Gonyleptidae (e.g., as in Machado & Oliveira 1998, 2002; Buzatto et al. 2007) and some other families most notably Stygnopsidae and Cranaidae (e.g., Machado & Warfel 2006; Hunter et al. 2007), but also in some Cosmetidae (e.g., as per Goodnight & Goodnight 1976). In such cases, females can forgo foraging or other activities to persistently guard the eggs (reviewed in Machado & Mac´ ıas-Ord ´ o˜ nez 2007). Paternal care in harvestmen, however, typically involves a male caring for eggs of varying ages and can include continuous mating with multiple females that approach, resulting in eggs being placed together from several different mothers (reviewed in Requena et al. 2014). In such cases, the male will usually spend time cleaning eggs and protecting them from fungal infection and cannibalism (Mora 1990; Machado & Raimundo 2001). Initially, male harvestmen were believed to be less effective at egg care than females (Hara et al. 2003; Machado et al. 2004), but more recent studies have shown that there is no difference in success between maternal and paternal care (Requena et al. 2009). Below, we provide a series of non-standardized observations on a Honduran harvestman, Cynorta bromeliacia Goodnight & Good- night, 1947, from the family Cosmetidae, which were made with the objective to provide an outline of seemingly novel behavior for the species and to encourage further in-depth studies of paternal care in this and other cosmetids. No techniques were applied to mark individuals (e.g., florescent paint, etc.), although we were able to easily determine individual sex in the field through direct observation of external anatomy (or in two cases from photographs). There is slight external sexual dimorphism in our focal species, which Goodnight & Goodnight (1947, p.22) described originally from the same locality where we made our behavioral observations. Those authors specified that adult males of C. bromeliacia have the ‘‘Distal portion of the fourth femur somewhat widened, with a row of ten or twelve larger tubercles on either side’’ and ‘‘Basitarsus of first tarsus slightly enlarged.’’ From our observations of many individuals in 2012 and thereafter, we were able to visually identify the sex of all observed individuals by these attributes, noting that while the distal femur of the fourth leg of mature males is indeed incrassate (i.e., ‘‘somewhat widened’’) and has slight armature compared to females (i.e., row of tubercles), the latter consists of up to 15 tubercles on both dorsal and ventral surfaces. In addition, for males, the basitarsus of the first leg is better characterized as being slightly swollen, while also the male chelicerae can be marginally enlarged in comparison to females. Over the course of multiple field seasons (all June to August, mainly 2012–2013) at Cusuco National park (15829.8 0 N À 15832.1 0 N, 88813.0 0 W À 88816.3 0 W), Department Cort ´ es, Honduras, the cosmetid Cynorta bromeliacia was observed engaging in behaviors that would indicate that this species exhibits paternal care of eggs and even of recently hatched juveniles. Our first observation of this kind was made in the month of June 2012 in the early morning (at around //titan/production/a/arac/live_jobs/arac-49/arac-49-01/arac-49-01-01/layouts/arac-49-01-01.3d  19 April 2021  9:42 am  Allen Press, Inc.  Customer MS# MS# JoA-S-19-028 Page 151 151