3.2 Morphotype assignment and phylogeny estimation
Based on LM images we recovered two named species and six undescribed morphotypes (Hansenocaris demodex from Green I., Taiwan and Sesoko I., Okinawa; H. itoi from the White Sea, Russia; Type A* from Green I., Sesoko I., and the Azores; Type C from Sesoko I., Type D* from WangHaiXiang harbor, Taiwan and Sesoko I.; Type I* from the Azores; and Type AE* from Taiwan), with morphotype designations following Dreyer et al., submitted). To this were added four specimens that could not be morphotyped prior to sequencing due to lack either of images or any voucher material (Facetotecta sp. 1 from Antarctica and Facetotecta sp. 5 from Sesoko Island; Fig. 1).
Our alignment contained 81 specimens (of which seven are non-imaged and voucherless “Facetotecta sp.” sequences), 6730 bps, 1680 distinct patterns, 1443 parsimony-informative sites, 384 singleton sites and 4903 constant sites (Table 3). Following the best substitution-model fit inferred by ModelFinder, we merged the partitions as follows: TNe+R2 (18S rDNA; BIC-score 14930.890, LnL: -24693.263), TIM2+F+R2 (H3, all codons; BIC-score 6798.637, LnL: -24693.133), TN+F+I+G4 (28SrDNA; BIC-score 12621.319; LnL N/A), TPM2+F+I (12SrDNA; 3435.374, LnL N/A) and GTR+F+G4 (16S rDNA, COX1, all codons; BIC-score11902.261, LnL: -24705.039) (Table 3). We recovered two clades (I and II), although the monophyly of the second one was not well-supported (Clade I: 98.6% Ultrafast Bootstrap (UFBoot), 93% SH-aLRT support; Clade II: 66.6% UFBoot, 81% SH-aLRT; Fig. 1).
In Clade I the planktotrophic morphotype A* is paraphyletic (97.5% UFBoot/96% SH-aLRT). The placement of three Type A* specimens from the Pacific (TA-2018-096, JA-2019-126) and the Azores (AZ-2019-5) within a highly supported, monophyletic subclade comprising pigmented and yolky lecithotrophs (95.8% UFBoot/71% SH-aLRT support). The relationship between Types C, D*, and H. demodex remains unresolved in our data set (Fig. 1; 69.2% UFBoot/32% SH-aLRT). In our dataset, all the Clade II specimens and morphotypes are planktotrophic, although the feeding type of Facetotecta sp. 5 and Antarctic species 1 and 2 is unknown. All multi-specimen morphotypes in the clade are monophyletic with high support, including an unnamed morphotype from the Azores (“Unnamed y-nauplius”; AZ-2019-1, 2, 4, 6, 7, 9; 90.3% UFBoot/99% SH-aLRT), Type AE* (100 UFBoot/100% SH-aLRT) and H. itoi (99.9% UFBoot/100% SH-aLRT).