The evolutionary history of chelicerate metallothioneins reveals de novo emergence and metal-binding specialization across the subphylum

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  The evolutionary history of chelicerate metallothioneins reveals de novo emergence and metal-binding specialization across the subphylum Abstract Metallothioneins (MTs) are a diverse family of proteins involved in metal homeostasis and detoxification, enabling organisms to adapt to varying metal availability across ecosystems. While extensively studied in vertebrates and gastropods, MTs remain poorly characterized in many arthropods, particularly chelicerates. Identifying and characterizing chelicerate MTs is therefore key to deciphering how this diverse group of animals –which includes spiders, scorpions, and ticks– copes with metal-related challenges in different environments. In this study, we have identified over 450 MTs from 221 chelicerate species and classified them into three structurally and phylogenetically distinct types: MT1, MT2, and MT3. Bidomain MTs are the most widespread across chelicerate lineages, while short monodomain forms and large variants occur in specifi...

New records and defensive behaviour of a rarely seen tarantula, Trichopelma coenobita (Simon, 1889) on Trinidad, West Indies

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New records and defensive behaviour of a rarely seen tarantula, Trichopelma coenobita (Simon, 1889) on Trinidad, West Indies

The subfamily Trichopelmatinae of the family Theraphosidae Thorell, 1869 (tarantulas) comprise 31 described species. They are known only from the New World, particularly the Caribbean, Central and South America (Mori and Bertani 2020). However information on the ecology and behaviour of this group is sparse.

Trichopelma coenobita was originally described as Stothis coenobita Simon 1889, based on a female specimen from Venezuela. Decades later, a male T. coenobita was described for the first time, thanks to a new observation of a male-female pair on Trinidad in February 1964. In this report, we present two additional observations of this tarantula species on Trinidad, expanding its known geographic distribution. These findings supplement the following earlier records of their presence on the island: January 1945 and February 1968, location 10°21’N, 61°13’W; 10-22 February 1964 -Arima Valley; and 14-26 July 1978 - Blanchisseuse (Mori and Bertani 2020). West (1984) misidentified a specimen of T. coenobita from the Textel Station, Blanchissuese Road, as Cyriocosmus elegans, which also occurs there (Sherwood et al. 2022).

Most striking is the number of distinctive physical features, most notably the abdominal pattern, that distinguish T. coenobita from other sympatric theraphosids. Although Mori and Bertani (2020) described their physical characteristics in detail, not much could be said about Trichopelma coenobita reproduction, natural behaviour, prey preference and hunting strategies or conservation status.