Botryllophilus angustus Kim &amp; Boxshall 2021, sp. nov.
Creators: name: Kim, Il-Hoi
name: Boxshall, Geoff A.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Cyclopoida
Ascidicolidae
Botryllophilus
Botryllophilus angustus

description: <i>Botryllophilus angustus</i> sp. nov. (Figs. 54-56) <b>Type material.</b> Holotype &amp;female; (MNHN-IU-2018-1971) and paratype &amp;female; (dissected, MNHN-IU-2014-17375) from <i>budẚstçma</i> sp.; Mabul, Malaysia, OPHG 1067 -S (04º14.51’N, 118º37.32’E), depth 5-20 m, CRRF coll., 16 January 2004. <b>Etymology.</b> The name of the new species is derived from the Latin <i>angust</i> (=narrow), indicating the narrow body. <b>Description of female.</b> Body (Fig. 54A, B) narrow, consisting of broader anterior and narrower posterior parts; body length 1.45 mm, width 0.33 mm. Cephalosome longer than wide. Anterior part of body gradually broadening posteriorly, unsegmented, but with 4 dorsal traces of articulations. Posterior part of body (Fig. 54C) not articulated from anterior part, consisting of genital and 4 abdominal somites. Genital somite much wider than long, with complicated, densely sclerotized sculpture on ventral surface; genital apertures positioned dorsally. Four abdominal somites clearly defined, 112×154, 127×140, 119×127, and 135×110 μm, respectively. Caudal ramus (Fig. 54D) armed with 4 claws and 1 seta; 1 of 2 outer distal claws massive and blunt, other outer claw not articulated from ramus. Rostrum absent. Antennule (Fig. 54E) 120 μm long, 4-segmented; first and second segments broadened; ar- mature formula 9 (3 large + 6 small), 4 (2 large + 2 small), 2 (1 large + 1 small), and 12. Left antenna (Fig. 54F) 4-segmented; proximal 3 segments unarmed; terminal segment (second endopodal segment) about 2.7 times longer than wide (59×22 μm), armed with 7 bluntly tipped setae. Terminal segment of right antenna (Fig. 54G) about 3.3 times longer than wide (69×21 μm), longer than that of left antenna; all setae distally capped with finely serrate membrane, 3 outer setae on distal margin shorter than those of left antenna. Labrum weak, easily destroyed. Mandible (Fig. 54H) consisting of coxa and palp; coxal gnathobase with 4 teeth including 2 distal acutely-pointed, longer teeth; palp with 9 setae arranged as 3, 2, 2, and 2. Maxillule (Fig. 54I) consisting of precoxa and palp; precoxa with 6 distinct setae on arthrite; palp divisible into coxa, basis, and endopod; coxa with 1 vestigial seta on epipodite; basis with 2 setae on medial margin, 3 setae on outer margin, and setulose lobe distally; endopod articulated from basis, distinctly wider than long, armed with 3 setae. Maxilla (Fig. 55A) indistinctly 3-segmented, armed with 3, 4 and 3 setae on first to third segments, respectively. Maxilliped (Fig. 55B) 4-segmented; syncoxa with 2 small setae on inner margin; basis with 1 rudimentary seta on inner margin; first endopodal segment unarmed; second endopodal segment with 1 rudimentary seta on inner margin and 1 minute denticle at inner distal corner; terminal claw small, bearing minute subdistal denticle. Legs 1-4 (Figs. 55 C-F, 56A-D) biramous, asymmetrical, with unsegmented exopods and 2-segmented endopods; coxa unarmed; basis with outer seta and row of spinules at inner distal corner. Second endopodal segment of right legs 2-4 with mix of spines and setae. Numbers of spines (Roman numerals) and setae (Arabic numerals) on right and left legs 1-4 as follows: Leg 5 (Fig. 56E, F) small, about 1.4 times longer than wide (86×60 μm), strongly tapering, armed with 4 setae (1 proximal and 3 distal), distal longest seta 114 μm, distinctly longer than segment. Leg 6 (Fig. 55G) represented by 1 spinule and 1 spiniform process on genital operculum; several dentiform elements on surface immediately adjacent to leg 6. <b>Male.</b> Unknown. <b>Remarks.</b> The exopods of right legs 1-4 of <i>B</i>. <i>angustus</i> <b>sp. nov.</b> are armed with 7, 6, 6, and 6 armature elements, respectively (the combination 7-6-6-6). This combination is common in members of the type B group (species with 5 or more annulations in the abdomen), but is very rare in members of the type A group, because the exopod of right leg 4 in type A usually bears 4 or 5 spines. In the type A group only two species, <i>B</i>. <i>nçrvegẚcus</i> and <i>B</i>. <i>angustus</i> <b>sp. nov.</b>, deviate from this pattern, although in the former species the combination may be either 7-6-6-6 or 7-6-6-7. <i>Bçtryllçphẚlus nçrvegẚcus</i> does not require detailed comparison with <i>B</i>. <i>angustus</i> <b>sp. nov</b>., because it carries distinctive features, such as the swollen metasome and the elongate and curved leg 5. In <i>BK angustus</i> <b>sp. nov.</b> the antenna is armed with 7 setae and leg 5 is very small. Both of these features are shared with three congeners, <i>B</i>. <i>dẚstẚnctus</i>, <i>B</i>. <i>mẚllarẚ</i> Ooishi, 2014, and <i>B</i>. <i>tuberculatus</i> <b>sp. nov.</b> However, all three of these species bear 5 setae on the second endopodal segment of right leg 4, and differ from <i>B</i>. <i>angustus</i> <b>sp. nov.</b> which has 2 spines and 3 setae on that segment of right leg 4.
description: Published as part of <i>Kim, Il-Hoi &amp; Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, pp. 1-286 in Zootaxa 1</i> on pages 88-91, DOI: 10.11646/zootaxa.4978.1.1, http://zenodo.org/record/4820443