Bryocyclops trangensis, Watiroyram, 2018

Watiroyram, Santi, 2018, Two new species of the genus Bryocyclops Kiefer, 1927 (Copepoda: Cyclopoida: Cyclopidae) from southern Thailand, Raffles Bulletin of Zoology 66, pp. 149-169 : 159-168

Bryocyclops trangensis , new species

( Figs. 8–13 )

Type locality. Khao Pina cave in Wat [=temple] Tham Khao Pina located in Nawong Subdistrict , Huai Yot District , Trang Province, southern Thailand ( Figs. 1A, 1C ). The coordinates of the entrance are 07°44′55.30′N, 99°31′36.81′E; altitude 34 m a.s.l. The cave is about 150 m long, with several pools filled exclusively with water dripping from stalactites. A rimstone pool in the dark zone, with about 10–20 L was selected as the location type. The water temperature during sampling was 22.0°C, pH 8.0, and conductivity was 350 μS cm−1 .

Material examined. Holotype: an adult female was dissected and mounted on a slide in glycerol and sealed with nail polish, NHMUK 2017.511 . Allotype : an adult male was dissected and mounted on a slide in glycerol and sealed with nail polish, NHMUK 2017.512 . Paratypes : three undissected females and males were preserved by 70% ethanol in a 1.5 mL microtube, NHMUK 2017.513 – 518 ; three undissected females with egg sacs and males were preserved by 70% ethanol in a 1.5 mL microtube, NPU 2017.003 . Additional materials : four undissected females and males were mounted on SEM Stub ( NPU 2017.003 S) .

All specimens were collected from Khao Pina cave by the author on 27 November 2016.

Diagnosis. Adult female: anal operculum is ovate and serrated. P1–P4 have acute projections on the distal margins, P1 has inner coxal seta, which are lacking on P2–P4. P1 has an inner basal spine. P1–P3 have two-segmented Enp and Exp; P4 has one-segmented Enp and two-segmented Exp. Setal and spine formulae on (1) Exp-2 P1–P4 as 5.5.5.4 and 3.3.3.3, respectively; (2) Enp-2 P1–P3 as 3.4.5 and 1.1.1, respectively; (3) Enp P4 has four setae and one spine, with an outer spiniform process.

Adult male: P1, P2, and Exp P3-P4 are as in female. Enp- 2 P3 has four pinnate setae and one strong transformed seta and spine. The transformed spine has a less-produced outstretched part, located near the tip of the spine. P4 Enp is two-segmented; the Enp-1 has one inner pinnate seta and one spiniform process on the outer distal corner plus two strong, short, spine-like processes along the inner margin; Enp-2 has three pinnate setae and one spiniform spine, with a spiniform process on the outer distal corner.

Description. Female ( Figs. 8 , 9 ), body length: 490–570 μm (mean: 550 μm; n = 10). Naupliar eye not discernible. Cephalothorax expanded laterally at cephalosome, with transverse scar on posterior end of cephalosome dorsally ( Fig. 8A ). Cephalosome, pedigers 2–5, and genital double-somite covered with fine refractile points. Posterior dorsal margins of cephalosome and pedigers 2–4 with smooth hyaline membrane; pediger 5 with irregularly serrated hyaline membrane ( Figs. 8A, 8B ). Genital double-somite and two succeeding urosomites with irregularly serrated hyaline membrane on the entire posterior margin ( Figs. 8 B–D, 9A). Genital double-somite symmetrical, anterior part expanded laterally, about 1.4 times wide as long, with a pair of dorsal sclerotised; single copulatory pore situated mid-ventrally. Anal somite ( Figs. 8 B–D, 9A, 9B) with a row of strong spinules on the entire posterior margin except nearly insertion point of anal operculum.

Anal operculum ( Figs. 8B, 8D , 9B ) ovate, small and irregularly serrated along its distal margin, not reaching the middle of caudal ramus, with a pair of dorsal sensilla on its base.

Caudal rami ( Figs. 8 B–D, 9A, 9B) symmetrical rectangular, about 2.3 times long as wide, with well-developed longitudinal dorsal keel, extended nearly the entire caudal ramus length. All seta pinnate, except seta VI; seta VII articulated at its base. Anterolateral accessory seta (I) absent. Anterolateral seta (II) shorter than caudal ramus, inserted near the middle of ramus dorsally. Posterolateral seta (III) about 1.5 times as long as caudal ramus, with strong spinules at its insertion laterally and ventrally. Outer terminal seta (IV) and inner terminal seta (V) with fracture plane, about 5.0 and 9.0 times as long as caudal ramus, respectively. Terminal accessory seta (VI) thin, shorter than 1/2 of caudal ramus. Dorsal seta (VII) about 2.0 times as long as caudal ramus, inserted on distal end of keel.

Rostrum ( Fig. 10A ) fused to cephalosome, free margin round and unornamented.

Antennule ( Figs. 10B ) short, not reaching posterior margin of cephalosome, 11-segmented. Setal formula as follows (A = aesthetasc, S = spine): 7.2.5.2.0.2.3.1+A.2.2.7+A.

Antenna ( Fig. 10C ) four-segmented, comprising coxobasis and three-segmented Enp. Coxobasis with smooth seta on inner distal corner. Enp-1 with smooth seta on inner medial margin. Enp-2 with five smooth setae along inner distal margin (one proximal and four distal setae) and row of tiny spinules along outer margin. Enp-3 with seven smooth setae on distal end: one inner, four apical and two outer.

Mandible ( Fig. 10D ) short and robust, with four strongly chitinised teeth on gnathobase plus a smooth seta on innermost margin. Mandibular palp reduced, with one smooth seta.

Maxillule ( Fig. 10E ) with three-segmented. Praecoxal arthrite with two strong apical claws, one spine on distal margin and one spine, five setae on inner margin. Maxillular palp twosegmented, with four and three smooth setae on coxobasis and Enp, respectively.

Maxilla ( Fig. 10F ) with five-segmented. Praecoxal endite with two apical pinnate setae. Coxa with smooth seta on proximal endite and two smooth setae on distal endite. Basis with one apical claw-like expansion, one strong spine and one seta inserted at base of claw. Enp-1 with one smooth inner seta. Enp-2 with one strong and two thin apical setae.

Maxilliped ( Fig. 10G ) with four-segmented. Syncoxa with one spiniform and one smooth seta on distal inner margin accompanied by row of strong spinules along middle outer surface. Basis with one spiniform seta on middle inner margin and row of strong spinules on distal outer margin. Enp with two-segmented, with one spiniform seta and two smooth setae on proximal and distal segments, respectively. Armament of legs 1–4 as follows (legend: outer-inner seta/ spine; outer-apical-inner; Arabic numerals indicate setae; Roman numerals indicate spines):

P1 ( Fig. 11A ) intercoxal plate with acute projections on distal margin. Coxa with inner seta. Basis with slender seta on outer margin and stout spiniform spine on inner margin. Two-segmented Exp and Enp. Exp-1 much smaller than Exp-2, with one outer spine. Exp-2 twice as long as wide, with three inner pinnate setae, two apical pinnate setae and three outer spines. Enp-1 with one inner pinnate seta. Enp-2 with one apical spiniform spine and three pinnate setae (one inner, one apical and one outer).

P2 ( Fig. 11B ) intercoxal plate, and Exp similar to P1. Coxa without inner seta. Basis with one slender outer seta. Twosegmented Enp, Enp-1 with inner seta, Enp-2 with one apical spine and four pinnate setae (two inner, one apical and one outer).

P3 ( Fig. 11C ) intercoxal plate, coxa, basis and Exp similar to P2. Two-segmented Enp, Enp-1 with inner seta, Enp-2 with one apical spine and five setae (three inner, one apical and one outer). All setae pinnate.

P4 ( Fig. 11D ) intercoxal plate with acute projections on distal margin. Coxa without inner seta. Basis with slender seta on outer margin. Exp with two-segmented, Exp-1 with outer spine. Exp-2 with two inner pinnate setae, two apical pinnate setae and three outer spines. Enp with one-segmented, with spiniform process on outer margin, ornamented with apical spine and four pinnate setae (two inner, one apical and one outer).

P5 ( Fig. 10H ) fused to fifth thoracic somite, with three pinnate setae: outermost seta longest, inserted on small prominence; middle and innermost setae directly inserted to somite, former seta shorter than latter.

P6 ( Figs. 8B, 8D , 9C ) reduced to simple plate on genital double-somite laterodorsally, with lateral pinnate seta, middle minute spinule and inner naked seta.

Adult females each have a pair of egg sacs, each with three eggs.

Male ( Figs. 12–13 ) slightly smaller than female. Body length, excluding caudal setae, 500–560 μm (mean = 530 μm; n = 5). Body shape similar to female, except in genital segment and urosomal segmentation ( Fig. 12A ). Antenna, mouthparts, anal operculum, caudal rami ( Figs. 9E , 10 C–G), P1–P2, P5 ( Figs. 12C , 13A, 13B ), P3–P4 exopods ( Figs. 13 C– D), similar to those in females.

Antennule ( Fig. 12D ) 15-segmented. Setal formula as follows (A = aesthetasc, S = spine): 8+A.5.2.2+A.0.4.1.0.2.3.S.1+A.S.1.8+A. All setae smooth.

P3 ( Fig. 13C ) Enp two-segmented, Enp-1 smaller than Enp-2. Enp-1 with inner pinnate seta. Enp-2 with one transformed spine apically, four pinnate setae (two inner, one apical, one outer) and one strong transformed seta on distal inner margin; transformed spine with outstretched part less-produced, located nearly its tip.

P4 ( Fig. 13D ) Enp two-segmented. Enp-1 bigger than Enp- 2, with inner pinnate seta and two short, strong spines on inner surface. Enp-2 smaller, with inner seta, apical seta and spine and outer seta; all setae pinnate.

P6 ( Figs. 9F , 12B, 12C ) reduced to simple plate, represented by three pinnate setae.

Variability. P1 Exp-2 of male with six setae on one ramus (only one individual of ten examined males).

Etymology. The specific name trangensis refers to the place “ Trang ” where the new species was found, the Latin suffix “- ensis ” is an adjective for the place.

Remarks. Bryocyclops trangensis , new species, also fits with the generic and Group II characteristics as described for B. muscicoloides , new species. Bryocyclops trangensis , new species, is most similar to B. muscicola by the posterior margin of urosome and anal operculum serrated, the present of inner coxal seta on P1, Enp-2 P1 having four elements, the female Enp-2 P3 having six elements, the shape and setation of the female Enp P4 (five elements), and the male Enp-2 P4 of males having four elements. Bryocyclops trangensis , new species, can be easily distinguished from B. muscicola in the morphological differences in both sexes: Enp-2 P2 has five elements in B. trangensis , new species, but four elements in B. muscicola , and Exp-2 P2–P3 of B. trangensis , new species, have normal setae but those in B. muscicola have two blunt setae. The female P4 Enp of B. trangensis , new species, has subequal three setae but B. muscicola has apical seta remarkably longer than the others. Bryocyclops trangensis , new species, has certain typical characteristics in the male P3–P4: Enp-1 P4 has two strong, spine-like outgrowths on its inner surface, which are absent in B. muscicola ; Enp-2 P3 of B. trangensis , new species, has four pinnate setae and one transformed seta while B. muscicola has one smooth and three pinnate setae; the outstretched part of the transformed spine on Enp-2 P3 is not well-produced in B. trangensis , new species, but is well-produced in B. muscicola .

Bryocyclops trangensis , new species, differs from B. bogoriensis by a P1–P4 intercoxal plate with an acute projections on distal margin that is more rounded in B. bogoriensis and the P1 Enp having inner coxal seta only in the new species. The male P3 Enp-2 of the new species has larger setae than those in B. bogoriensis; there are one transformed and four normal setae in the new species but only four normal setae in B. bogoriensis. The outstretched portion of the transformed species on the male P3 Enp-2 is less produced compared to those in B. bogoriensis, which are semi-circular. The male P4 Enp-1 of the new species has two spiniform outgrowths on the inner margin but is smooth in B. bogoriensis.

Bryocyclops trangensis , new species, is different from B. fidjiensis by its anal operculum ovate, which is serrated but triangular and smooth in the later species, and P4’s twosegmented Exp and one-segmented Enp in the female in the new species but one-segmented Exp and two-segmented in both sexes in B. fidjiensis . The female P4 Enp of the new species has one spine and four setae but one spine and three setae in B. fidjiensis ; and the distal exopod of P4 has three spines in the new species but four spines in B. fidjiensis . The male P4 Enp-1 of the new species has two outgrowths on the inner margin that are absent in B. fidjiensis .

Bryocyclops trangensis , new species, differs from B. caroli in both sexes by the following: anal operculum is finely serrated in the new species but coarsely serrated in B. caroli ; Enp-2 P2 of the new species has four setae but three in B. caroli ; and Exp-2 P2–P3 of the new species have no blunt setae compared to two in B. caroli . The female P4 Enp of the new species has four subequal setae but one typically long seta and three equal setae in B. caroli . The new species has two spiniform outgrowths on the inner margin in the male P4 Enp-1, but this is absent in B. caroli . The male P3 Enp-2 of B. trangensis , new species, has four setae, one transformed spine and seta compared to four setae and one transformed spine in B. caroli . The transformed spine of the new species has an acute tip and a short distance between the outstretched part and its tip, but there is a blunt tip and a long distance in B. caroli .

Bryocyclops trangensis , new species, and B. campaneri are different from each other as follows: the posterior margins of pediger 2–4 dorsally are smooth in B. trangensis , new species, but B. campaneri has transverse crenulated frills; P2 Enp-2 has four setae in the new species but three setae in B. campaneri ; and P2–3 Exp-2 has no blunt setae compared to two in B. campaneri . The female P4 Enp of the new species has no outgrowth near the innermost seta but there is a large rounded outgrowth in B. campaneri . The transformed spine on the male P3 Enp-2 of the new species has an outstretched part that is less developed and located close to its tip, but it is well-produced into a semi-circular shaped and located near the mid-length of the spine for B. campaneri .

Figures

Fig. 8. Bryocyclops trangensis, new species, female. A, habitus, dorsal view; B, pediger 5, genital double-somite and urosome, dorsal view; C, genital double-somite with spermatophores and urosome, ventral view; D, genital double-somite with spermatophores and urosome, lateral view. Scale bar = 100 µm.

Fig. 9. Bryocyclops trangensis, new species, female (A–C) and male (D–F). A, genital double-somite and urosome, ventral view; B, anal somite and caudal ramus, dorsal view; C, P6; D, pediger 5, genital somite and urosome, dorsal view; E, anal somite and caudal ramus, dorsal view; F, pediger 5, genital somite and urosome, lateral view.

Fig. 10. Bryocyclops trangensis, new species, female. A, rostrum; B, antennule; C, antenna; D, mandible; E, maxillule; F, maxilla; G, maxilliped; H, P5. Scale bars = 100 µm.

Fig. 11. Bryocyclops trangensis, new species, female. A, P1; B, P2; C, P3; D, P4. Scale bar = 100 μm.

Fig. 12. Bryocyclops trangensis, new species, male. A, habitus, dorsal view; B, genital somite and urosome, ventral view; C, pediger 5, genital somite and urosome, lateral view; D, antennule. Scale bar = 100 µm.

Fig. 13. Bryocyclops trangensis, new species, male. A, P1; B, P2; C, P3; D, P4. Scale bar = 100 μm.

Fig. 1. Sampling localities and habitats for new species in southern Thailand (A–C). A, sampling localities, black circle (l) = Khao Plu cave from Chumphon Province for B. muscicoloides, new species, and black square (N) = Khao Pina cave from Trang Province for B. trangensis, new species; B and C, habitat for B. muscicoloides, new species and B. trangensis, new species, respectively.