Pseudechinolaophonte, Song & Lee & Kim & George & Khim, 2023

Pseudechinolaophonte gen.nov.

Diagnosis.

Laophontidae T. Scott, 1905. Body elongate, cylindrical, podoplean boundary between pro- and urosome inconspicuous. Sexual dimorphism in the A1, P3, P5 and P6; female with GDS. Cphth almost squarish, reaching about 1/3 of total body length; dorsally with spinulose, broad cuticular projection bearing 2-4 apical spikes on posterior margin (cf. Fig. 9A View Figure 9 ). Rostrum small, laterally constricted, square, fused to cphth. Thoracic body somites with paired strong spikes centrally on the posterior margin (cf. Fig. 9A View Figure 9 ); abdominal somites, except telson, dorsally with sclerotised clasp-like area bearing 2 spikes on posterior margins (cf. Fig. 9A View Figure 9 ). First abdominal somite (posterior half of female GDS) and second abdominal somite laterally with well-developed, wing-like epimeres (cf. Fig. 9A View Figure 9 ). Pre-anal somite with well-developed pseudoperculum, with 2 strong tridentate spikes (cf. Fig. 9A View Figure 9 ), but with some variability. CR at the most twice as long as broad, with 7 setae. Female A1 slender, 6-segmented; male A1 7-8-segmented, subchirocer. A2 with 1-segmented exopod bearing 4 setae, allobasis with or without abexopodal seta; endopod 1-segmented, with 2 lateral spines and 1 seta; 1 spine modified with a rounded tip that differs between the species; apically with 5-6 setae/spines, 2-3 of which geniculate. Mxp prehensile, with elongated syncoxa and basis; syncoxa with 1-2 setae on its apical edge. Endopod produced into long claw that surpasses the length of the basis. P1 prehensile, with elongated coxa and basis, but none reaching the length of enp-1. Exopod 2-segmented, not reaching half the length of the enp-1. Exp-1 about twice as long as exp-2, with 1 outer spine; exp-2 with 3 outer spines and 2 apical setae. Endopod 2-segmented, enp-1 long, without any ornamentation; enp-2 small, apically with strong serrated claw and 1 tiny seta. P2-P4 with 3-segmented exopods, P2 and P4, as well as female P3 endopods 2-segmented; outer basal seta of P2 biplumose, with extremely long pinnae. Male P3 and P4 sexually dimorphic; male P3 exopod more compact than in female, endopod 3-segmented, second segment with pronounced apophysis. Male P4 exopod also stronger than in female, somewhat bent inwards. P4 endopods particularly small in both sexes, not reaching the distal margin of exp-1. Female P5 with baseoendopod bearing 2 setae; exopod distinct, with 3 setae. Male P5 with completely reduced baseoendopod, exopod with 3 setae. Female P6 very small, knob-like, with 2 tiny setae. Male P6 small, consisting of simple lobe carrying 1 small bare and 1 long biplumose seta.

Etymology.

The generic name is composed of the Greek prefix pseudo -, meaning false or fake and the generic name Echinolaophonte . Gender: feminine.

Type species.

Pseudechinolaophonte minuta (Cottarelly & Forniz, 1991), gen. et comb. nov., by original designation.

Additional species.

Ps. mordoganensis (Kuru, Sönmez & Karaytug, 2019) gen. et comb. nov., Ps. veniliae (Cottarelly, Forniz & Bascherini, 1992), gen. et comb. nov.

Restructuring Echinolaophonte Nicholls, 1941

After the exclusion of Parechinolaophonte tropica gen. et comb. nov., Pseudechinolaophonte minuta gen. et comb. nov., Ps. mordoganensis gen. et comb. nov. and Ps. veniliae gen. et comb. nov. from Echinolaophonte -CS, the genus Echinolaophonte retains 11 species (Fig. 10 View Figure 10 , node M). They can be characterised by the synapomorphic dorsal spur on the posterior margin of the cphth (Table 2 View Table 2 , character 54). This dorsal cuticular spur on the posterior margin of the cphth is quite rare in Harpacticoida , had been recognised as a characteristic feature for Echinolaophonte by Nicholls (1941) and is hypothesised here as a strong synapomorphic character for all 11 species.

Phylogenetic relationships within Echinolaophonte

Echinolaophonte splits into two main subordinated clades, namely the Echinolaophonte armiger - Echinolaophonte gladiator clade enclosing E. armiger and E. gladiator (Fig. 10 View Figure 10 , node N) and the Echinolaophonte brevispinosa - Echinolaophonte mirabilis clade that includes the remaining eight species (Fig. 10 View Figure 10 , node Q). The monophyly of the Echinolaophonte armiger - Echinolaophonte gladiator clade is supported by five autapomorphies (Table 2 View Table 2 , characters 55-59) and each species is also characterised by four autapomorphies (Table 2 View Table 2 , characters 60-67).

The Echinolaophonte brevispinosa - Echinolaophonte mirabilis clade is characterised by seven unambiguous autapomorphies (Table 2 View Table 2 , characters 68-74). It splits again into two subordinated clades, i.e. the Echinolaophonte brevispinosa - Echinolaophonte oshoroensis clade (Fig. 10 View Figure 10 , node R) and the Echinolaophonte villabonae - Echinolaophonte mirabilis clade (Fig. 10 View Figure 10 , node W). Both clades are supported by four and two autapomorphies, respectively (Table 2 View Table 2 , characters 75-78 and 103, 104, respectively) and also, the relationships within the subclades can be supported by some apomorphic characters (Table 2 View Table 2 ). Within the Echinolaophonte villabonae - Echinolaophonte mirabilis clade, a further splitting took place: the Echinolaophonte villabonae - Echinolaophonte briani clade encompasses E. villabonae and E. briani (and tentatively E. hystrix ) (Fig. 10 View Figure 10 , node X), whose status as sister species is supported by six synapomorphies (Table 2 View Table 2 , characters 105-110). Together they constitute the sister taxon of the Echinolaophonte tetracheir - Echinolaophonte mirabilis clade (Fig. 10 View Figure 10 , node AA), whose monophyly is supported by four autapomorphies (Table 2 View Table 2 , characters 115-118). Within the Echinolaophonte tetracheir - Echinolaophonte mirabilis clade, the first branch-off is E. tetracheir (Fig. 10 View Figure 10 , node BB), forming the sister species of the Echinolaophonte musa - Echinolaophonte mirabilis clade (Fig. 10 View Figure 10 , node CC). All named species can be characterised by distinct autapomorphies that are discussed in detail below.

Establishment of Echinolaophonte briani Lang, 1965

Lang (1965) reported and described a new presumed subspecies from Dillon Beach, California (U.S.A.), which he named E. armiger f. briani Lang, 1965. He assumed a close relationship with E. armiger f. typica sensu Gurney (1927), but at the same time, noted some morphological differences that justified, in his opinion, the establishment of a new form (subspecies) Echinolaophonte briani . Based on the detailed re-description of E. armiger by Lee et al. (2006), as well as on the here presented detailed phylogenetic analysis, it became clear that Lang’s (1965) E. armiger f. briani in fact represents a distinct species that is closely related to E. villabonae . Thus, it is here elevated to species rank as Echinolaophonte briani Lang, 1965.

The status of Echinolaophonte hystrix and Laophonte steueri van Douwe, 1929

Echinolaophonte hystrix had been synonymised with E. armiger by Nicholls (1941) and later by Lang (1948) as Onychocamptus armiger . Lee et al. (2006) provided a well-justified re-instatement of E. hystrix and, at the same time, recognised that Lang’s (1965) description of E. armiger f. typica (Gurney, 1927) most probably was a re-description of Brian’s (1928) E. hystrix , whose underlying Mediterranean material had been donated to K. Lang by A. Brian ( Lang 1965: 5). The argumentation given by Lee et al. (2006) is adopted here and the identity of E. hystrix is confirmed.

Van Douwe (1929) described another species from the French, Italian and Croatian Mediterranean coast, Laophonte steueri . That author provided a quite detailed textual description that lacks, however, a similarly detailed set of illustrations. He pointed towards the strong similarity of L. steueri with L. horrida and L. brevispinosa , apparently unaware of Brian’s (1928) description of L. hystrix . Like the latter, also L. steueri was subsequently synonymised with E. armiger by Nicholls (1941) and Lang (1948). The WoRMS database synonymises L. steueri with Echinolaophonte hystrix ( Walter and Boxshall 2022), albeit without mentioning the corresponding literature that might justify that synonymisation.

The here presented phylogenetic analysis aimed at elucidating the systematic relationship of both E. hystrix and L. steueri . However, the available information is scarce and the descriptions of both species are rather imprecise and incomplete. Though, the synonymisation of L. steueri with E. hystrix is tentatively confirmed here (see Discussion); however and despite some indications for an allocation of E. hystrix into the Echinolaophonte villabonae - Echinolaophonte briani clade, due to the gap of detailed information, the systematic position of E. hystrix within Echinolaophonte remains unclear (Fig. 10 View Figure 10 , node X).

Diagnostic key to the genera and species of Echinolaophonte and the here established new genera (note: E. longantennata was excluded from the analysis due to lack of data)