BASAL LAOPHONTID EVOLUTION 



95 



Labrum with spinular patches on anterior face but no overlapping 

 scales. 



Mandible (Fig. 27B) with short gnathobase and small 2-seg- 

 mented palp representing free endopod and fused basis and exopod; 

 endopod a minute segment with 3 pinnate setae; basal armature 

 represented by 2 lateral pinnate setae, exopod represented by single 

 seta. 



Paragnaths highly ornate lobes as in E. bulbifera. 



Maxillule (Fig. 27C) with elongate arthrite bearing 1 seta on 

 anterior surface and 9 elements around distal margin. Coxal endite 

 with 1 spine and 1 seta, basal endite with 1 spine and 2 setae. Exopod 

 a short segment with 2 distal setae; endopod incorporated into basis, 

 represented by 2 setae. 



Maxilla (Fig. 27D). Syncoxa with very long setules around outer 

 margin and few additional spinule rows as figured; with 3 endites; 

 praecoxal endite small, with 1 naked seta; middle endite drawn out 

 into spine, with 2 setae; distal endite with 3 elements. Allobasis 

 produced into strong curved claw; accessory armature consisting of 

 2 setae. Endopod incorporated into allobasis, represented by 3 bare 

 setae. 



Maxilliped (Fig.27E) compact, basis and endopodal claw not 

 particularly elongate. Syncoxa with 2 pinnate setae. Basis with 

 spinular ornamentation as figured; spinules present along entire 

 palmar margin. Endopod represented by stout, minutely pinnate 

 claw bearing 1 accessory seta and tube-pore at base. 



PI (Fig. 27F) with dense ornamentation on praecoxa, coxa and 

 basis. Basis with pinnate seta on anterior surface and along outer 

 margin. Exopod large, 3-segmented; exp-1 with pinnate outer seta; 

 exp-3 with 2 unipinnate outer spines and 2 geniculate setae apically. 

 Endopod robust and relatively short; enp- 1 about 2.2 times as long 

 as basis, with long setules along inner margin and fine spinules along 

 outer margin; enp-2 about as long as wide, with short unipinnate 

 claw and small accessory seta. 



P2-P4 (Figs 28A-C) with 3-segmented exopods and 2-segmented 

 endopods. P2 basis with long, bipinnate outer spine; P3-P4 bases 

 with bare outer seta. P2 enp-1 with pinnate inner seta, P3-P4 enp-1 

 unarmed. Inner seta of P2 exp-2 reduced. Outer spine of P2-P4 enp- 

 2 setiform, very long in P4. Pore present near distal outer corner of 

 P3-P4 enp-2. Armature formula as for genus. 



P5 (Fig. 28D). Endopodal lobe well developed, extending to 

 halfway down the exopod; with 2 reduced bare setae apically, and 2 

 long widely separated setae along inner margin; pores present near 

 articulation with exopod, at base of apical setae and proximal to 

 innermost seta. Exopod relatively short, produced apically into short 

 tubular extension bearing 1 bare seta; inner margin with 1, outer 

 margin with 4 pinnate setae; inner seta slightly longer than apical 

 one. Both baseoendopod and exopod with spinulation as figured. 



MALE. Unknown. 



Remarks. The discovery of B. compacta at 2765 m depth at the 

 North Fiji Ridge represents the deepest record thus far for the family 

 Laophontidae (Lee & Huys, 1999). It displays a mozaic of primitive 

 (7-segmented 9 antennule; 3-segmented PI exopod; 9 P5 endopodal 

 lobe with 5 setae/spines) and advanced characters (P3-P4 enp-1 

 without inner seta; P3-P4 exp-3 with 1 inner seta) which serves to 

 distinguish the species from other esolinids. 



Status of Esola Spelaea (Chappuis, 1938) 



Lang (1944, 1948) placed Laophonte spelaea in the genus Esola 

 without giving any explicit reasons. From his generic diagnosis and 

 the phylogenetic scheme presented on p. 1450 (Lang, 1948), one can 



infer that his course of action was based solely on the presence of an 

 outer spine on the distal endopod segment of P2. Although this 

 character was diagnostic for Esola in Lang's sense it is clearly a 

 symplesiomorphy shared by all genera in the Archilaophonte -Esola 

 lineage (with the exception of Mourephonte) and consequently of no 

 value in inferring relationships. Lang (1944, 1948) subdivided 

 Esola into two species groups, diagnosed by the number of setae on 

 the male P5 endopodal lobe and the armature of the P3 in both sexes. 

 His spelaea-group included only E. spelaea and has until now 

 remained monotypic. It differed from the longicauda-group in the 

 presence of 2 setae (rather than 1 or 0) on the 6 P5 endopodal lobe 

 and a reduced armature on the P3 exopod (exp-3 with only 2 outer 

 spines) and endopod (enp-2 9 with only 2 inner setae; endopod 6* 

 without inner seta on enp-2 and with only 3 setae on enp-3). 



Chappuis' (1938) description is very brief and provides illustra- 

 tions of the male P2-P5 only. Unfortunately the author did not give 

 any information about the position of the setae on the female P5 

 which could have provided the justification for including L. spelaea 

 in the Archilaophonte-Esola lineage since in all of its members (1) 

 the proximal seta of the endopodal lobe is medially displaced and (2) 

 the insertion sites of the 2 proximal setae of the exopod are superim- 

 posed. Chappuis' statement that there are 4 setae on the baseoendopod 

 and 5 or 6 setae on the exopod can be interpreted in the light of this 

 generalized pattern. His reservation about the correct number of 

 exopodal setae might indicate the close or overlapping position of 

 some of these elements. Secondly, due to its strong medial displace- 

 ment the proximal endopodal seta has frequently been overlooked or 

 lost during dissection (Thompson & A. Scott, 1903; Norman, 1911; 

 Monard, 1926, 1928; Noodt, 1955), leaving open the possibility of 

 a similar observational error made in Chappuis' (1928) description. 

 The actual number of endopodal setae on the female P5 of L. spelaea 

 could therefore be five rather than four. Chappuis'(1928) armature 

 formula of P2 exp-3 tabulated as 222 (i.e. with 2 outer spines) is 

 unlikely to be correct when both P2 and P4 reportedly have 3 outer 

 spines on exp-3. No laophontid described thus far displays a [3-2-3] 

 outer spine pattern for P2-P4 and hence we suspect 123 (as in B. 

 compacta) to be the correct formula for P2 exp-3. 



Chappuis (1938) described L. spelaea from three caves in Apulia, 

 southern Italy (Abisso and La Zinzulusa near Castro, Grotta dei 

 Diavoli near Badisco) and regarded it as a marine relict. The caves 

 exhibit a tidal regime but the salinity approaches that of freshwater 

 ('. . . das Wasser schmeckt aber fast suss') which appears to be 

 confirmed by the presence of the stygobiont mysids Spelaeomysis 

 bottazzii Caroli and Stygiomysis hydruntina Caroli and the 

 palaemonid Typhlocarls salentina Caroli, all of which are endemic 

 to coastal caves and phreatic waters in the Apulia region. Both Pesce 

 (1985) and Rouch (1986) consider the species as a descendant from 

 a marine ancestral stock which successfully colonized subterranean 

 freshwater habitats via littoral karstic systems, possibly during 

 regression periods in the Tertiary ('Regression Model Evolution'). 



Laophonte spelaea cannot be accommodated in any of the exist- 

 ing laophontid genera. It appears to be related to Bathyesola in 

 certain aspects (see above) but differs from it in the presence of an 

 inner seta on P3-P4 enp- 1 , only 2 inner setae on P3 enp-2 and more 

 primitive setal formula on the P4 exopod. In view of the strong 

 ecological divergence between B. compacta and L. spelaea we 

 prefer to establish a new genus for the latter. The male P3 endopod 

 in Troglophonte gen. nov. does not accord with the pattern found in 

 the other esolinid genera. The absence of an inner seta on the middle 

 segment could be related to the reduced 1.221 pattern in the female 

 but might also indicate a relationship with a large group of other 

 laophontid genera which typically lose the proximal inner seta 

 during male P3 ontogeny. 



