Arecoidae James, Csuzdi & Brown, 2023

Misirlioğlu, Mete, Reynolds, John Warren, Stojanović, Mirjana, Trakić, Tanja, Sekulić, Jovana, James, Samuel W., Csuzdi, Csaba, Decaëns, Thibaud, Lapied, Emmanuel, Phillips, Helen R. P., Cameron, Erin K. & Brown, George G., 2023, Earthworms (Clitellata, Megadrili) of the world: an updated checklist of valid species and families, with notes on their distribution, Zootaxa 5255 (1), pp. 417-438 : 421-422

Arecoidae James, Csuzdi & Brown, 2023 Fam. nov.

Type genus: Areco Righi, Ayres & Bittencourt, 1978

Diagnosis: Crassiclitellata with quadrangular body, and dorsal post-clitellar groove. Four pairs of closelypaired, regularly distributed hook-shaped setae. Dorsal pores present. Genital pores microscopic. Long muscular esophagus, but no gizzard. No calciferous glands, no prostates or copulatory pouches. Intestine begins in XXXVII, typhlosole present. Pretesticular spermathecae, ovaries in XIII. Moniliform hearts in segments VIII to XI. No subneural vessel. Nephridia holoic, without bladders. Metandric, with one pair of testicles and seminal funnels in segment XI. Seminal vesicles in XII to XV.

Etymology: This new family name derives from the genus name Areco which with the species name reco is derived from “arecoreco”, originally in the Tupi indigenous language, meaning to confuse or to mix something up ( Drumond 1952).

Considerations: The intriguing aqua-megadrile (sensu Jamieson 1988) species Areco reco was described by Righi et al. (1978) from four specimens collected at the Reserva Ducke near Manaus, Amazonas ( Brazil) in 1975. Type specimens are deposited in the Instituto Nacional de Pesquisas da Amazonia (INPA) collection in Manaus. The authors placed the species tentatively in Sparganophilidae , but emphasized that the exact position of Areco was uncertain. They claimed similarity with Glyphydrilocrius by shape of body and organization of digestive system, and with Sparganophilus by presence of pretesticular spermathecae, though this is a feature shared with several other South American families (e.g., Glossoscolecidae , Rhinodrilidae ). Furthermore, Sparganophilus and Glyphydrilocrius are holandric, while Areco is metandric. Additional Areco specimens were collected at the type locality by S. James and S. Tapia-Coral in 2012 ( Erséus et al. 2020), and molecular phylogenomic analyses revealed it to be sister to Rhinodrilidae , and far from Sparganophilidae and other semi-aquatic families ( Erséus et al. 2020). Nonetheless, Arecoidae shows important genetic divergence and major morphological differences with Rhinodrilidae , lacking gizzard and calciferous glands, so we propose here the erection of this new monotypic family to accommodate its only species and genus.