Elaphoidella isana Watiroyram & Sanoamuang & Brancelj 2021, sp. nov.
Creators: name: Watiroyram, Santi
name: Sanoamuang, La-Orsri
name: Brancelj, Anton
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Hexanauplia
Harpacticoida
Canthocamptidae
Elaphoidella
Elaphoidella isana

description: Elaphoidella isana sp. nov.
(Figs. 2–6)
“(http://zoobank.org/ urn:lsid:zoobank.org:act: 7A63FD88-5292-4B23-8E84-3B5557EEC9F8)”
Type locality. Pha Dam Cave, Na Ngua Subdistrict, Nam Som District, Udon Thani Province, northeastern Thailand; coordinates of the cave entrance: 17°46’14.38”N, 102°12’36.72”E; altitude: 223 m a.s.l. (Fig. 1A–C).
Material examined. Holotype: adult female, length 420 µm (access no: NHMUK 2019.1001), completely dissected and mounted on one slide. Paratypes: five adult females, stored in 70% ethanol (access nos: NHMUK 2019.1002 - 1006, NPU 2019-1). All specimens were collected from the type locality on October 23, 2016 by Santi Watiroyram.
Etymology. Elaphoidella isana sp. nov. is named after the Isan region (Thai name for northeastern part of Thailand) from where the specimens were collected. The species epithet is a feminine singular adjective.
Distribution. Known only from the pools fed by dripping water from the type locality.
Description of female. Body length measured from anterior margin of rostrum to posterior margin of caudal rami: 420–540 µm (mean = 450 µm, n = 5). Habitus elongate, subcylindrical, width evenly decreasing from cephalothorax to last urosomite; preserved specimens colourless (Fig. 2A–B). Naupliar eye not discernible. Cephalothorax with well discernible integumental saddle-shaped window; prosomites and urosomites with serrated posterior margins (Figs. 2C; 3A; 4A–C). Genital double-somite completely fused (Figs. 2A–C; 3A), about 0.9 times as long as wide, with row of strong spinules on distal dorso-lateral margin; two short rows of small spinules ventrally near insertion of P6. Genital complex (Fig. 3A) with large, bell-shaped median copulatory pore. Urosomites 3 and 4 with row of robust spinules dorso-laterally, laterally and ventro-laterally; urosomite 4 with row of small spinules ventrally located in middle of row. Anal somite (Figs. 2C–D; 3A–C; 4B–E) with one pair of sensilla dorsally at base of insertion of anal operculum; two strong spinules laterally and one strong spinule ventrally positioned at inner corner of base of each caudal ramus.
Anal operculum (Figs. 2C–D; 3C; 4D) well developed, slightly extending beyond anal somite; with 25 (range: 24–26) strong spinules on free margin.
Caudal ramus (Figs. 2C–D; 3A–C; 4D–E) asymmetrically conical, about 1.5 times as long as wide, with well developed dorsal keel; with oblique dorso-lateral row of spinules and row of spinules along distal inner margin; with prominent plate extending over base of caudal setae. Setae I–III and VI–VII bare and thin. Anterolateral accessory seta (I) slightly shorter than caudal ramus, inserted at about 1/4 of caudal ramus length. Anterolateral seta (II) short, inserted just below of seta I. Posterolateral seta (III) inserted at about middle of caudal ramus length, as long as seta I, with two strong spinules at its base. Outer apical seta (IV) about as long as caudal ramus, unipinnate, without breaking plane. Inner apical seta (V) longest, without breaking plane. Inner accessory seta (VI) slightly longer than seta III. Dorsal seta (VII) articulated, as long as seta III, inserted on keel at half length of caudal ramus.
Antennule (Fig. 5A) eight-segmented, not reaching to middle of cephalothorax. Both aesthetascs fused with seta at its base (forming acrothek on apical segment), proximal one larger and longer than distal one. Setal formula: 1, 9, 5, 2 + a, 1, 3, 2, 7 + a.
Antenna (Fig. 5B) comprising coxa, allobasis, and one-segmented Exp and Enp. Coxa slightly shorter than wide, unornamented. Allobasis about three times as long as wide, with four thin spinules on median margin. Onesegmented Exp with two unipinnate setae subapically and two unipinnate setae apically, similar in length. Enp about five times as long as wide, with two strong spines laterally and several strong spinules along margin; apically with five elements: one strong unipinnated spine, one normal bare seta, three geniculate setae; external surface of Enp with two transverse rows of tiny spinules on distal part and thin seta inserted sub-apically.
Mandible (Fig. 5C) robust, with six strong chitinized teeth and one unipinnate seta on gnathobase. Mandibular palp two-segmented; proximal segment with one bare seta on distal corner; distal segment with one seta laterally and four setae apically, all setae bare.
Maxillule (Fig. 5D) robust. Praecoxal arthrite with seven robust unipinnate spines; bare, slender seta on anterior surface. Coxal endite with one bipinnate seta. Basis with two bare, slender setae, one strong bipinnate seta apically. Enp and Exp represented by two bare, slender setae each.
Maxilla (Fig. 5E) short, robust. Syncoxa with two endites, each with one bare and two unipinnate setae inserted apically; row of long spinules inserted on outer margin of syncoxa. Basal endite drawn out into strong, claw-like apophysis, with few spinules distally, two bare setae laterally; Enp represented by one bare seta.
Maxilliped (Figs. 4F; 5F) prehensile. Syncoxa with spinules proximally and distally. Basis three times as long as wide, with 18–20 spinules on inner margin, additional two rows of small spinules on outer margin proximally and distally. Enp drawn into unipinnate claw, curved inwards; with bare thin seta at its base.
P1 with three-segmented Exp and Enp, P2–P4 with three-segmented Exp and two-segmented Enp. P1–P4 intercoxal sclerites with concave free margin without ornamentation. Distribution of spinules as indicated on Fig. 6A–D. Armature formula of P1–P4 as follows (legend: inner-outer seta/spine; inner-apical-outer; Arabic numerals represent setae, Roman numerals represent spines):
P1 (Fig. 6A) Enp slightly longer than Exp; Enp-1 about 3.2 times as long as wide, with unipinnate seta on inner margin distally. Enp-2 three times as long as wide, with one bare seta at inner corner distally. Enp-3 four times as long as wide, with one bare seta laterally, one geniculate and one unipinnate seta apically. Exp-1 about twice as long as wide, with one unipinnate spine on outer margin distally. Exp-2 as long as Exp-1 with one bare seta on inner margin distally and one unipinnate spine on outer margin distally. Exp-3 about three times as long as wide, with one geniculate seta on inner margin subapically, one geniculate seta and one unipinnate spine apically, and one unipinnate spine on outer margin distally.
P2 (Fig. 6B) Enp about half length of Exp-2. Enp-1 shorter than wide, with bare seta on inner margin. Enp-2 oval, about 2.5 times as long as wide; with two bare setae on inner margin, shorter than segment; two bipinnate setae, equal in length apically, about three times as long as segment; one spiniform seta apically, shorter than segment. Exp-1 and Exp-2 about 1.5 times as long as wide. Exp-1 and Exp-2 with one bipinnate spine on outer margin distally, Exp-2 with one bipinnate seta on inner margin distally. Exp-3 four times as long as wide; with one bipinnate seta on inner margin inserted in middle of segment, two bipinnate setae and one bipinnate spine on apical margin, apical setae unequal in length, longest one about twice as long as segment; outer margin with one bipinnate spine inserted at about 3/4 of margin.
P3 (Fig. 6C) Enp as in P2 but additional unipinnate seta on inner margin of Enp-2; apical setae longer than in P2 Enp, about four times as long as segment. Exp as in P2 but inner setae of Exp-2 and Exp-3 with unipinnate tips on inner margin (normal in P2) and long, robust spines with rounded tips on Exp-1 and Exp-2 (in contrast pointed in P2).
P4 (Fig. 6D) Enp shorter than Exp-1. Enp-1 small, with one bare seta on inner margin. Enp-2 rectangular, four times as long as wide, with two unipinnate setae on inner margin, longer than segment; apical margin with one seta, about four times as long as segment, and one spiniform seta slightly shorter than segment. Exp relatively long. Exp- 1 about 2.5 times as long as wide; Exp-2 about four times as long as wide, Exp-3 about five times as long as wide. Setae on inner margin of Exp-2-3 as in P3. Exp-3 seta of apical margin about 1.5 as long as segment. Spines on Exp-1-2 with pointed tips, spines of outer margin of Exp-3 bare, spine of apical margin unipinnate.
P5 (Fig. 6E) seta on outer margin of baseoendopod long, thin, bare. Exp and baseoendopod well separated. Tip of baseoendopod reaching half of Exp length. Baseoendopod with four long, strong spiniform setae; three inner setae equal in length; outermost seta about half as long as longest one. Exp oval, with five elements: inner seta (I) as long as segment, spiniform; apical seta (II) longest, about four times as long as segment; outer seta (III) robust, spiniform, slightly longer than segment; two outermost setae (IV–V) thin, bare, very short.
P6 (Fig. 3A) fused, forming reduced small simple plate located near base of copulatory tube; with two setae on each side, inner seta longer than outer one.
Variability. The only morphological variability was observed in the body size, varying from 420 to 540 µm (n = 5).
Male. Unknown
description: Published as part of Watiroyram, Santi, Sanoamuang, La-Orsri & Brancelj, Anton, 2021, New species of Elaphoidella Chappuis, 1929 and Schizopera Sars, 1905 (Copepoda Harpacticoida) from two caves in northeastern and southern Thailand, pp. 550-569 in Zootaxa 5051 (1) on pages 553-559, DOI: 10.11646/zootaxa.5051.1.22, http://zenodo.org/record/5563968