104 



R. HUYS AND W. LEE 



proximal aesthetasc typically fused to 2 setae (except Archilao- 

 phonte). Antennary exopod with 4 well developed setae. Mandible 

 typically biramous (except Applanola and Mourephonte). Maxilla 

 with 3 endites on syncoxa. Maxilliped with 2-3 setae on syncoxa. 

 PI with 2- or 3-segmented exopod, retaining full complement of 

 setae (0.0.022 or 0.023); enp-1 occasionally with inner seta. P2 enp- 

 2 with outer spine (except Applanola) or entire P2 endopod absent 

 {Mourephonte). P3 endopod 8 retaining proximal inner seta of 9 

 enp-2 (except for Troglophonte where it is lost in both sexes). 

 Armature formula as follows: 



Exopod 



Endopod 



P2 

 P3 

 P4 



0.1.123 



0.1.(1-2)23 



0.1.(1-2)23 



0-1.(1-2)2(0-1) or absent 



0-1.321 



0-1.221 



P5 9 with separate rami; exopod elongate, with 6 setae/spines; 

 proximal two setae along outer margin with superimposed insertion 

 sites; baseoendopod trapezoid, slightly developed, with 4-5 setae/ 

 spines. P5 <? without endopodal lobe (except for Archilaophonte, 

 bearing 2 long setae), no endopodal armature; exopod 5 setae/ 

 spines. 



Typically with cup-shaped transformed pores on cephalothorax, 

 genital (double-)somite, and/or caudal rami. 



Type GENUS. Esola Edwards, 1891 



OTHER GENERA. Mourephonte Jakobi, 1953; Archilaophonte 

 Willen, 1995; Applanola gen. nov.; Archesola gen. nov.; Bathyesola 

 gen. nov.; Corbulaseta gen. nov.; Troglophonte gen. nov. 



Laophontinae T. Scott, 1905 



Antennule 3 with up to 3 segments distal to geniculation; proximal 

 aesthetasc fused to 1 seta. Mandible typically uniramous. Maxilliped 

 with maximum 2 setae on syncoxa. PI enp-1 without inner seta. P2 

 enp-2 without outer spine. P3 endopod 6 typically not retaining 

 proximal inner seta of 9 enp-2 (except for Laophonte cornuta-group 

 and Onychocamptus). 



Proximal outer setae of 9 P5 exopod with distinctly separated 

 insertion sites. 



Cup-shaped transformed pores on cephalothorax, genital (double-) 

 somite, and/or caudal rami never present. 



TYPE GENUS. Laophonte Philippi, 1840 



Other genera. Fifty-five; see Lang ( 1 948), Bodin (1997), George 

 (1997) and Lee & Huys (1999) for complete list. 



KEY TO GENERA OF ESOLINAE 



1. P2 endopod absent Mourephonte Jakobi, 1953. 



P2 endopod present, 2-segmented 2. 



2. Antennulary segment 2 with large spinous process along anterior 

 margin; P2 enp-2 with 1 inner seta; P5 baseoendopod S with 2 long 

 setae Archilaophonte Willen, 1995. 



Antennulary segment 2 without spinous process along anterior margin; 

 P2 enp-2 with 2 inner setae; P5 baseoendopod £ without setae 3. 



3. Antennule 2 6-segmented; PI exopod 2-segmented; caudal rami with 

 medial or ventral modified pores 4. 



Antennule 9 7-segmented; PI exopod 3-segmented; caudal rami with- 

 out such pores 6. 



4. Body short, dorsoventrally flattened; P2 enp-2 outer spine absent; P3 



exopod 6 strongly modified Applanola gen. nov. 



Body elongate, sub-cylindrical; P2 enp-2 outer spine present; P3 exopod 

 6* not modified 5. 



5. Antennulary segment 1 with 3 spinous processes along posterior mar- 

 gin; distal inner seta of P4 endopod not transformed; caudal rami $ 

 modified, with bulbous swelling dorsally, ventrally and medially 



Esola Edwards, 1891. 



Antennulary segment 1 without distinct spinous processes; distal inner 

 seta of P4 endopod transformed; caudal rami not sexually dimorphic, 

 cylindrical Corbulaseta gen. nov. 



6. P3-P4 exp-3 with 1 inner seta; P3-P4 enp-1 without inner seta 



Bathyesola gen. nov. 



P3-P4 exp-3 with 2 inner setae *; P3-P4 enp-1 with inner seta 7. 



7. P3 enp-2 with 3 inner setae; P3 endopod 3 2-segmented; P5 

 baseoendopod with long articulating setophore in both sexes 



Archesola gen. nov. 



P3 enp-2 with 2 inner setae; P3 endopod 6 3-segmented; P5 



baseoendopod of both sexes without articulating setophore 



Troglophonte gen. nov. 



* Note that Chappuis' (1938) setal formula of P3 exp-3 can also be 

 interpreted as 123, implying the presence of only 1 inner seta. 



ECOLOGICAL RADIATION OF ESOLINAE 



Although none of the 1 8 species can be considered as truly cosmo- 

 politan, the subfamily as a whole occurs in all oceanic basins, 

 including the Antarctic Ocean. Superimposing habitat utilization 

 upon the phylogeny presented in Fig. 32 reveals an interesting but 

 complex ecological radiation pattern. Esolinae are essentially shal- 

 low water inhabitants, however, the variety of additional habitats 

 exploited by this lineage is startling for its small number of known 

 species. Considered against the background of the overwhelming 

 evolutionary success of their sister-lineage Laophontinae, esolinids 

 can be viewed as relicts of a formerly diverse group. 



Lee & Huys (1999) reviewed published deepwater records of 

 Laophontidae and regarded the colonization of the deep sea by this 

 family as remarkably unsuccessful. There is no single lineage 

 containing all deepwater forms, and the three exclusively bathyal 

 genera in the Laophontinae, Cornylaophonte Willen, Weddellao- 

 phonte Willen and Bathylaophonte Lee & Huys can be considered as 

 independent colonists of this habitat. Colonization of the deep sea by 

 the Esolinae follows a similarly erratic trend with early attempts by 

 the monotypic genera Archilaophonte in the Antarctic and Bathyesola 

 in the western Pacific. Within the genus Esola, E. profunda repres- 

 ents a third, secondary deepwater invasion derived from a shallow 

 water inhabiting ancestral stock (Fig. 32). 



According to Pesce (1985) and Rouch (1986) the genus 

 Troglophonte is likely to be derived from a marine ancestor stranded 

 during the lowering of sea level during the Tertiary. It is highly 

 endemic to freshwater lenses in several Apulian caves in southern 

 Italy (Chappuis, 1938). These caves are separated from the littoral 

 zone by macroporous karstic rock and exhibit a detectable tidal 

 current which appears insufficient to ensure substantial mixing of 

 the water inside the caves. The strong stratification with freshwater 

 lenses overlying the poorly oxygenated deeper layers has clearly 

 prevented the establishment of a diverse marine benthic fauna. 

 Rather than considering Troglophonte a Tethyan relict, its present 

 restricted distribution can also be regarded as a relatively recent 

 landward habitat range extension from a primarily shallow-subtidally 

 residing ancestral stock. Although some Laophontidae are regularly 



