BASAL LAOPHONTID EVOLUTION 



67 



Description. 



FEMALE. Body length from anterior margin of rostrum to posterior 

 margin of caudal rami 510 um; maximum width 120 urn (Vervoort, 

 1964). 



male. Body length from anterior margin of rostrum to posterior 

 margin of caudal rami 401 um (n=3; range: 389^15 um). Maxi- 

 mum width (121 um) measured at posterior margin of cephalothorax. 



Body (Fig. 1 1 A) more compact and abbreviated than in 9; covered 

 with similar dense pattern of minute spinules. Cephalothorax with 

 small cup-shaped pores anterodorsally and anteroventrally on either 

 side of rostrum; wider than free somites; without transverse spinule 

 row dorsally. Urosome distinctly narrower than prosome; none of 

 urosomites with backwardly produced posterolateral corners. 



Genital somite with ventrolateral cup-shaped pores (Fig. 1 1 B-C). 

 Sixth legs (Fig. 11B-C) represented by well developed opercula, 

 one articulating and closing off left or right genital aperture; each 

 produced into cylindrical process bearing 1 lateral and 1 apical seta. 



Antennule (Fig. 12A-D) 7-segmented, subchirocer, with 

 geniculation between segments 5 and 6. Segment 1 with spinules/ 

 setules around anterior margin and 2 spinous processes along poste- 

 rior margin. Segment 4 minute, represented by incomplete sclerite. 

 Segment 5 longest, with large proximal process anteriorly, bearing 

 modified spine; forming cylindrical process bearing long aesthetasc 

 fused basally to 2 setae (Fig. 12C). Segment 6 with 3 spinous 

 processes along anterior margin. Segment 7 triangular. Armature 

 formula: 1-[1 pinnate], 2-[7 + 2 pinnate], 3-[6], 4-[2], 5-[7 + 2 

 pinnate + 1 spine + (2 + ae)], 6-[l + 3 processes], 7-[7 + acrothek]. 

 Apical acrothek consisting of aesthetasc and 2 bare setae. 



Mandibular palp (Fig. 1 1 F) small, comprising elongate basis with 

 1 pinnate seta and free endopod bearing 3 apical setae. 



PI (Fig. 12E) with broader basal pedestal and more robust 

 endopod than in E. bulbifera; enp-1 stouter and enp-2 slightly 

 shorter. Exopod small; exp-1 not extending to distal margin of basal 

 pedestal, with stout outer spine; exp-2 with 3 outer setae and 2 apical 

 setae, outer apical seta much shorter than in 9 and not geniculate. 



P2-P4 without inner seta on enp-1 (Fig. 12F-H). P3 endopod 

 (Fig. 12G) 3-segmented; enp-1 as in 9; enp-2 with inner seta and 

 dentate outer apophysis; enp-3 small, with tube-pore, 2 lateral and 2 

 apical setae. Armature formula: 



Exopod 



Endopod 



P2 



0.1.123 



0.221 



P3 



0.1.223 



0.1.220 



P4 



0.1.223 



0.221 



[9:0.321] 



P5 (Fig. HE) medially fused, positioned ventrolaterally. 

 Baseoendopod without endopodal lobe; medial margin with 2 tube- 

 pores; outer basal seta arising from short spinulose pedestal. Exopod 

 free; with 1 inner seta and 1 apical plus 3 outer pinnate spines; spines 

 markedly shorter than in E. bulbifera. 



Caudal ramus (Fig. 11B-D) rectangular, without bulbiform ex- 

 pansions; about 1.7 times as long as wide; with medial cup-shaped 

 concavity as in 9 



Remarks. Vervoort (1964) inclined to assign specific status to his 

 material from the Ifaluk Atoll, however, refrained from doing so due 

 to the uncertainty about the widely recorded variability for E. 

 longicauda. E. vervoorti occupies an isolated position in the genus 

 for a number of reasons: (1) the absence of the inner seta on P2-P4 

 enp-1, (2) the dentate type of apophysis on the male P3 endopod, (3) 

 absence of transverse spinular row on cephalothorax, (4) reduced 



mandibular palp, (5) very short 9 caudal rami, and (6) the sexual 

 dimorphism of the outer apical seta on PI exp-2. The latter character 

 is unique within the Laophontidae; Vervoort (1964) also illustrated 

 this sexual dimorphism but did not mention it as a feature of high 

 significance. 



Esola longicauda Edwards, 1891 sensu Noodt (1955) 



Noodt ( 1955) illustrated a single ovigerous female off. longicauda 

 recorded from the Sea of Marmara. His specimen is much larger 

 (0.79 mm) than any other species in the genus (Table I) and like 

 Edwards ' (1891) types shows a strongly developed seta on P4 enp- 

 1. It resembles E. bulbifera in the bulbiform caudal rami and the 

 incompletely 7-segmented antennule which according to Noodt 

 (1955) displays a partly subdivided apical segment. His statement 

 that the endopodal lobe has only 3 setae is clearly based on an error. 

 Without further information the identity of this specimen cannot be 

 determined. 



Esola longicauda Edwards, 1891 var. sensu Vervoort 

 (1964) 



This variety, known from a single male, differs from Vervoort' s 

 (1964) typical specimens of E. longicauda (here designated as E. 

 vervoorti sp. nov.) in the slender and almost haplocer antennule, the 

 presence of an inner seta on P2-P4 enp- 1 and the shorter P4 endopod 

 and P5 exopod. This combination of characters rules out 

 conspecificity with both E. vervoorti and E. lobata, the only estab- 

 lished species from the Western Pacific. It also differs from Mielke's 

 (1997) Esola spec, from Sulawesi by the presence of 5 setae on the 

 distal exopod segment of PI. It is conceivable that this variety 

 represents yet another species, however, the discovery of the female 

 is crucial before it can be attributed such status. 



Esola longicauda Edwards, 1891 sensu Wells & Rao 

 (1986) 



Wells & Rao's (1986) record of a single female from Havelock 

 Island (South Andaman) is virtually indeterminable. It is probably 

 conspecific with Sewell's (1940) specimens of Laophonte bulbifera 

 recorded from Nankauri Harbour in the Nicobar Islands and Addu 

 Atoll in the Maldive Archipelago. Both share the absence of the 

 inner seta on P4 enp-1 and their antennulary segments have similar 

 proportional lengths. 



Esola spec, sensu Mielke (1997) 



Mielke (1997) provided figures and additional information of a 

 single female which is potentially sympatric with E. lobata in North 

 Sulawesi. This form differs from the latter in the size of the proc- 

 esses on the first antennule segment, the shape and setal length of the 

 antennary exopod, mandibular armature, PI exp-2 setation, pres- 

 ence of a vestigial seta on P4 enp-1 and caudal ramus shape. The 

 presence of only 4 setae on the distal exopod segment of PI relates 

 it to E. galapagoensis and E. longicauda, however, differences in 

 the antennules and P4 endopod make conspecificity unlikely. 



Genus Mourephonte Jakobi, 1953 



Moerephonte Jakobi, 1953: lapsus calami by Vervoort (1964). 



Jakobi (1953) established this genus to accommodate a new species 

 M. catharinensis described from the coast of Santa Catarina, Brazil. 

 Vervoort (1964) expressed severe doubts as to the validity of this 

 genus, assuming that the completely reduced P2 endopod and the 



