Echiniscidae in the Mascarenes: the wonders of Mauritius Author Kiosya, Yevgen https://orcid.org/0000-0002-6432-9089 School of Biology, V. N. Karazin Kharkiv National University, Svobody Sq. 4, 61022 Kharkiv, Ukraine Author Voncina, Katarzyna Department of Invertebrate Evolution, Faculty of Biology, Jagiellonian University, Gronostajowa 9, 30 - 387 Krakow, Poland Author Gasiorek, Piotr https://orcid.org/0000-0002-2814-8117 Department of Invertebrate Evolution, Faculty of Biology, Jagiellonian University, Gronostajowa 9, 30 - 387 Krakow, Poland piotr.lukas.gasiorek@gmail.com text Evolutionary Systematics 2021 2021-04-09 5 1 93 120 http://dx.doi.org/10.3897/evolsyst.5.59997 journal article http://dx.doi.org/10.3897/evolsyst.5.59997 2535-0730-1-93 22050C3440A54B7A9969222AE927D6AA 2B44BE75734D5AF8B3871CB1656D7A80 Echiniscus tropicalis Binda & Pilato, 1995 Figures 8 , 9 , 10 , 11 , Tables 6 , 7 , 8 Material. Together 402 adult females, 17 juveniles and 10 larvae mounted on slides. Description. Mature females (i.e. from the third instar onwards; measurements in Table 6 ). Body small and plump (Figs 9A , 11A ), yellow to orange, with minute red eyes absent after mounting. Ordinary primary and secondary (cephalic papillae) clavae of the Echiniscus -type; peribuccal cirri with well-developed cirrophores. Cirrus A very short (<25% of the body length), with cirrophore. Body appendage configuration A - B - C - Cd - D - Dd - E , with all appendages developed as spines or spicules, which are smooth or only sometimes spines E are serrated (Figs 9A , 10 , 11A ). Asymmetries frequent, especially in the lateral positions. Table 6. Measurements [in µm ] of selected morphological structures of mature females of Echiniscus tropicalis (pooled data from the populations ID.032, ID.939 and SG.001) mounted in Hoyer's medium (N - number of specimens/structures measured, Range refers to the smallest and the largest structure among all measured specimens; SD - standard deviation).
Character N Range Mean SD
µm sp µm sp µm sp
Body length 26 137 - 223 384 - 513 194 476 20 31
Scapular plate length 26 33.6 - 45.2 - - - 40.9 - 3.3 -
Head appendages lengths
Cirrus internus 24 10.0 - 14.5 22.2 - 36.0 12.3 30.0 1.3 3.1
Cephalic papilla 26 5.0 - 7.7 12.6 - 18.8 6.1 14.9 0.5 1.5
Cirrus externus 25 11.2 - 18.2 27.5 - 41.7 14.8 36.4 1.9 3.2
Clava 25 4.2 - 6.4 9.3 - 16.3 5.0 12.2 0.6 1.6
Cirrus A 25 17.9 - 33.8 41.1 - 79.3 27.8 68.1 3.7 8.2
Cirrus A /Body length ratio 25 9% - 18% - - - 14% - 2% -
Body appendages lengths
Spine B 24 4.3 - 12.7 9.9 - 29.4 8.5 20.8 2.4 5.5
Spine C 26 6.5 - 14.7 14.9 - 35.0 11.1 27.1 2.3 5.1
Spine Cd 26 3.0 - 10.8 7.7 - 25.0 6.7 16.4 1.7 4.0
Spine D 22 5.7 - 13.8 13.5 - 31.3 10.0 24.3 2.4 5.3
Spine Dd 25 4.3 - 14.9 9.9 - 35.0 10.2 25.1 2.6 6.3
Spine E 26 7.1 - 15.8 16.3 - 38.0 12.1 29.6 2.3 5.5
Spine on leg I length 26 1.9 - 3.7 4.2 - 8.8 2.6 6.4 0.5 1.1
Papilla on leg IV length 25 2.8 - 4.3 6.7 - 10.9 3.4 8.3 0.3 1.0
Number of teeth on the collar 25 8 - 17 - - - 12.3 - 2.3 -
Claw 1 heights
Branch 25 9.6 - 12.4 24.7 - 30.4 10.9 26.8 0.8 1.5
Spur 23 1.5 - 2.6 4.0 - 6.0 2.0 4.9 0.3 0.5
Spur/branch length ratio 23 15% - 21% - - - 18% - 2% -
Claw 2 heights
Branch 26 9.2 - 12.0 22.9 - 28.6 10.4 25.6 0.8 1.5
Spur 25 1.6 - 2.7 3.9 - 6.2 1.9 4.7 0.3 0.5
Spur/branch length ratio 25 16% - 23% - - - 19% - 2% -
Claw 3 heights
Branch 25 8.7 - 12.3 23.2 - 28.6 10.4 25.6 0.8 1.5
Spur 23 1.5 - 2.7 3.8 - 6.2 1.9 4.7 0.3 0.6
Spur/branch length ratio 23 15% - 23% - - - 18% - 2% -
Claw 4 heights
Branch 26 10.7 - 14.8 25.9 - 34.9 12.6 30.8 1.1 1.9
Spur 18 2.0 - 3.1 5.3 - 7.1 2.4 6.0 0.2 0.5
Spur/branch length ratio 18 18% - 24% - - - 20% - 2% -
Figure 9. Habitus of Echiniscus tropicalis in dorsolateral view (PCM): A adult female (black arrowheads indicate pulvini, whereas white arrowheads - pedal plates), B larva. Scale bars in μm . Dorsal plates strongly sclerotised and well-demarcated from each other, with the Echiniscus spinulosus type sculpturing, i.e. only pores are present (Figs 9A , 10 , 11 ). Pores are densely arranged and rather of uniform size. Dark endocuticular rings absent (Figs 10 , 11B, C ). The cephalic plate consists of two halves, with an anterior chalice-like incision. The cervical (neck) plate is in the form of a narrow grey belt, weakly delineated anterior to the scapular plate (Fig. 10 ). The scapular plate non-facetted, with the usual lateral sutures delineating small rectangular portions (Figs 9A , 10 ). Three median plates: m1, m3 unipartite, the latter reduced to a narrow stripe; m2 bipartite (Figs 9A , 10 , 11 ). Two pairs of large segmental plates, their narrower anterior portions with two thin belts devoid of sculpture (Fig. 10 ). The caudal (terminal) plate with evident incisions (Figs 9A , 10 ) and may be facetted (Fig. 11A ). Figure 10. Dorsal plate sculpturing of Echiniscus tropicalis in close-up (PCM). Scale bar in μm . Ventral cuticle smooth or with densely arranged endocuticular pillars. Sexpartite gonopore located anteriorly of legs IV and a trilobed anus between legs IV. Pedal plates and pulvini present (Fig. 9A ). Spine I thin and minute (Fig. 9A ). Dentate collar IV composed of numerous acute teeth (Figs 9A , 11A ). Papilla on leg IV present (Fig. 9A ). Claws IV slightly higher than claws I-III. External claws on all legs smooth. Internal claws with heteromorphic spurs positioned at ca. 1/4-1/3 of the claw height. Figure 11. Dorsal plate sculpturing of Echiniscus tropicalis (SEM): A adult female in dorsal view, B, C pores in close-up. Scale bars in μm . Mature males . Absent. Juveniles (i.e. from the second instar onwards; measurements in Table 7 ). No morphometric gap or qualitative differences between adult and juvenile females found. Gonopore absent. Table 7. Measurements [in µm ] of selected morphological structures of juveniles of Echiniscus tropicalis (population ID.939) mounted in Hoyer's medium (N - number of specimens/structures measured, Range refers to the smallest and the largest structure among all measured specimens; SD - standard deviation).
Character N Range Mean SD
µm sp µm sp µm sp
Body length 10 143 - 169 444 - 506 158 475 9 19
Scapular plate length 10 29.9 - 35.4 - - - 33.2 - 1.8 -
Head appendages lengths
Cirrus internus 9 7.6 - 9.6 22.4 - 29.0 8.7 25.8 0.8 2.2
Cephalic papilla 9 4.6 - 5.5 13.3 - 17.5 5.1 15.5 0.3 1.2
Cirrus externus 10 10.2 - 13.7 34.1 - 41.8 12.1 36.4 0.9 2.3
Clava 10 3.6 - 4.5 11.2 - 12.9 4.0 12.2 0.3 0.6
Cirrus A 9 22.2 - 25.6 63.3 - 78.0 23.4 71.1 1.3 5.3
Cirrus A /Body length ratio 9 13% - 16% - - - 15% - 1% -
Body appendages lengths
Spine B 9 3.5 - 7.4 10.4 - 22.8 5.3 15.7 1.5 4.4
Spine C 10 6.5 - 10.5 19.9 - 33.4 8.7 26.3 1.5 4.4
Spine Cd 10 4.6 - 7.9 14.1 - 24.4 6.5 19.6 1.0 2.9
Spine D 7 2.1 - 8.8 6.4 - 26.1 5.3 15.9 2.5 7.8
Spine Dd 10 10.1 - 14.3 28.9 - 42.2 11.4 34.2 1.3 3.8
Spine E 10 7.8 - 13.0 23.9 - 40.1 11.2 33.8 1.5 4.3
Spine on leg I length 10 1.8 - 2.6 5.3 - 7.9 2.1 6.2 0.2 0.8
Papilla on leg IV length 10 2.4 - 3.0 6.8 - 9.0 2.7 8.2 0.2 0.6
Number of teeth on the collar 10 7 - 12 - - - 10.3 - 1.7 -
Claw 1 heights
Branch 10 7.3 - 9.3 23.4 - 27.8 8.7 26.2 0.6 1.4
Spur 9 1.3 - 1.7 3.7 - 5.4 1.6 4.8 0.1 0.5
Spur/branch length ratio 9 16% - 22% - - - 18% - 2% -
Claw 2 heights
Branch 10 7.2 - 8.6 22.0 - 26.5 8.0 24.1 0.5 1.4
Spur 7 1.3 - 1.9 4.2 - 5.9 1.5 4.6 0.2 0.6
Spur/branch length ratio 7 17% - 22% - - - 19% - 2% -
Claw 3 heights
Branch 10 7.7 - 8.7 22.0 - 26.9 8.2 24.8 0.4 1.5
Spur 7 1.4 - 1.7 4.0 - 5.4 1.5 4.7 0.1 0.5
Spur/branch length ratio 7 17% - 21% - - - 19% - 2% -
Claw 4 heights
Branch 10 8.5 - 10.9 26.3 - 33.2 9.9 29.7 0.7 1.9
Spur 6 1.7 - 2.4 4.8 - 7.4 2.0 6.0 0.3 0.9
Spur/branch length ratio 6 17% - 24% - - - 21% - 3% -
Larvae (i.e. the first instar; measurements in Table 8 ). Clear morphometric gap between juveniles and larvae exists (compare Tables 7 , 8 ). Body appendage configuration A - Cd - Dd - E (Fig. 9B ). Anterior portions of paired segmental plates weakly sclerotised. Gonopore and anus absent. Table 8. Measurements [in µm ] of selected morphological structures of larvae of Echiniscus tropicalis (population ID.939) mounted in Hoyer's medium (N - number of specimens/structures measured, Range refers to the smallest and the largest structure among all measured specimens; SD - standard deviation).
Character N Range Mean SD
µm sp µm sp µm sp
Body length 3 110 - 124 559 - 574 119 567 8 7
Scapular plate length 3 19.4 - 22.0 - - - 21.0 - 1.4 -
Head appendages lengths
Cirrus internus 3 4.2 - 4.6 20.9 - 21.6 4.5 21.3 0.2 0.4
Cephalic papilla 3 3.7 - 4.1 18.5 - 19.1 3.9 18.7 0.2 0.3
Cirrus externus 2 6.0 - 6.4 29.6 - 30.9 6.2 30.3 0.3 0.9
Clava 3 2.6 - 3.1 13.4 - 14.4 2.9 13.9 0.3 0.5
Cirrus A 3 13.3 - 15.5 60.9 - 71.8 14.1 67.1 1.2 5.6
Cirrus A /Body length ratio 3 11% - 13% - - - 12% - 1% -
Body appendages lengths
Spine Cd 3 0.9 - 3.2 4.1 - 15.5 2.4 11.5 1.3 6.4
Spine Dd 3 3.2 - 6.0 16.5 - 27.8 4.8 22.8 1.5 5.8
Spine E 3 3.9 - 5.5 20.1 - 25.0 4.7 22.4 0.8 2.5
Spine on leg I length 3 1.2 - 1.6 6.2 - 7.4 1.5 7.0 0.2 0.7
Papilla on leg IV length 3 1.7 - 2.0 8.8 - 9.1 1.9 8.9 0.2 0.2
Number of teeth on the collar 3 6 - 7 - - - 6.7 - 0.6 -
Claw 1 heights
Branch 3 5.3 - 5.8 26.4 - 27.3 5.6 26.7 0.3 0.5
Spur 3 1.1 - 1.4 5.7 - 6.5 1.3 6.2 0.2 0.4
Spur/branch length ratio 3 21% - 25% - - - 23% - 2% -
Claw 2 heights
Branch 3 5.1 - 5.5 24.5 - 26.3 5.3 25.4 0.2 0.9
Spur 3 1.0 - 1.1 4.6 - 5.7 1.1 5.1 0.1 0.5
Spur/branch length ratio 3 18% - 22% - - - 20% - 2% -
Claw 3 heights
Branch 3 5.1 - 5.7 24.5 - 26.4 5.4 25.7 0.3 1.0
Spur 3 1.2 - 1.3 5.5 - 6.2 1.2 5.9 0.1 0.4
Spur/branch length ratio 3 22% - 24% - - - 23% - 1% -
Claw 4 heights
Branch 3 6.0 - 6.1 27.7 - 31.4 6.1 29.0 0.1 2.1
Spur 2 1.2 - 1.6 5.5 - 7.4 1.4 6.4 0.3 1.4
Spur/branch length ratio 2 20% - 27% - - - 23% - 5% -
Eggs . One egg per exuviae was found in few examined exuviae. DNA sequences and phylogenetic position. Two haplotypes in all markers were found, corresponding with the populations ID.032 and ID.939: 18S rRNA (MW327546, MW327547), 28S rRNA (MW327542, MW327543), ITS-2 (MW327549, MW327550), with the exception of ITS-1, characterised by one haplotype (MW327551, MW327552). The sister species of E. tropicalis within the Echiniscus spinulosus complex is E. siticulosus (Fig. 8 ). Phenotypic differential diagnosis. Echiniscus tropicalis was originally described based on two adult females ( Binda and Pilato 1995 ). We compared the newly found Southeast Asian specimens with the microphotographs of the holotype that confirmed our suspicions after reading the description, i.e. the lack of sound morphological discrepancies between the type material from the Seychelles and abundant material from the Malay Archipelago and the Malay Peninsula. The only difference is the serration of spines E that may be well-developed in Asian populations (Fig. 10 ), whereas this trait was not reported by Binda and Pilato (1995) . The original description mentions "primary and secondary points" in the paratype = a potential ramification. As there is a considerable intrapopulation variability regarding this trait, the Seychellois and Asian populations should be ascertained as conspecific unless DNA data from the Seychelles reject this hypothesis. There is a plethora of differences between adult females of E. insularis sp. nov. and E. tropicalis after the description of the latter was supplemented with new data: the presence of supernumerary spicules along the margins of dorsal plates and in the caudal incisions (present in E. insularis sp. nov. vs absent in E. tropicalis); the presence of pedal plates (absent in E. insularis sp. nov. vs present in E. tropicalis); the relative length of cirrus A (86.1- 106.2 in E. insularis sp. nov. vs 41.1- 79.3 in E. tropicalis); the absolute lengths of lateral spines B- D (B 2.5-3.2 μm , C 2.0-5.2 μm , D 2.5-4.0 μm in E. insularis sp. nov. vs B 4.3-12.7 μm , C 6.5-14.7 μm , D 5.7-13.8 μm in E. tropicalis); the presence of males (present in E. insularis sp. nov. vs absent in E. tropicalis); additionally, the spine E is frequently serrated in E. tropicalis (smooth in E. insularis sp. nov.).