taxonID	type	description	language	source
03DD87A5632CFF80FF1B1D7A4969F8A4.taxon	description	(Figs. 1 – 3)	en	Varela, Carlos, Walter, T. Chad (2026): A new species of Acanthomolgus Humes & Stock, 1972 (Copepoda: Cyclopoida) from the Red Sea, Egypt, with an updated key to species. Zootaxa 5741 (2): 353-364, DOI: 10.11646/zootaxa.5741.2.7, URL: https://doi.org/10.11646/zootaxa.5741.2.7
03DD87A5632CFF80FF1B1D7A4969F8A4.taxon	diagnosis	Diagnosis. Caudal rami as long as wide; antenna with two long claws almost the same length; maxillule with four elements; maxilliped segment 2 setae almost the same length; female genital segment with lateral margins nonparallel; P 1 exopod segment 1 outer spine in the is longer than the width of this segment; P 4 endopod segment 2 lacks inner spines. Female P 5 with a proximally swollen, lateral margin with row of small spinules, the longer terminal seta does not extend over caudal rami.	en	Varela, Carlos, Walter, T. Chad (2026): A new species of Acanthomolgus Humes & Stock, 1972 (Copepoda: Cyclopoida) from the Red Sea, Egypt, with an updated key to species. Zootaxa 5741 (2): 353-364, DOI: 10.11646/zootaxa.5741.2.7, URL: https://doi.org/10.11646/zootaxa.5741.2.7
03DD87A5632CFF80FF1B1D7A4969F8A4.taxon	materials_examined	Type material. All type specimens from Egypt, Ras Banas, Red Sea (23 ° 54 ’ N 35 ° 48 ’ E), no host data, no depth recorded, collected in 1950 by S. Vatikiotis. Holotype: non-ovigerous female USNM 1606769; Allotype: adult male, USNM 1606770; Paratypes: 18 females, 4 males USNM 1606771.	en	Varela, Carlos, Walter, T. Chad (2026): A new species of Acanthomolgus Humes & Stock, 1972 (Copepoda: Cyclopoida) from the Red Sea, Egypt, with an updated key to species. Zootaxa 5741 (2): 353-364, DOI: 10.11646/zootaxa.5741.2.7, URL: https://doi.org/10.11646/zootaxa.5741.2.7
03DD87A5632CFF80FF1B1D7A4969F8A4.taxon	description	Description. Adult female. (Fig. 1 A) Total Length 0.76 mm (mean = 0.73 mm), greatest width 0.45 mm (mean = 0.43 mm) prosome unusually broad, 0.54 mm long, occupying more than 71 % length of body. Cephalothorax with dorsal suture delimiting cephalosome and first pedigerous somite. Pedigerous somites 1 – 3 triangularly rounded lateral margins, somite 4 narrow with rounded lateral margins. Urosome (Fig. 1 B) 5 - segmented, caudal rami as long as wide. Genital double-somite 101 × 105 μm, almost as long as wide, distolateral margins produced laterally with small seta. Urosomites 1 – 3 length x width; 20 × 61, 16 × 57, 28 × 52 μm, respectively. Caudal rami (Fig. 1 E) 16 × 24 μm, ratio slightly wider than long, distolateral seta smooth, terminal 5 setae plumose. Egg sac not seen. P 5 (Fig. 3 B) free segment proximally swollen and elongate, 36 × 10 μm, ratio 3.6: 1, terminating in two unequal smooth setae, 25 μm (medial) and 18 μm (lateral). Rostrum (Fig. 1 C) triangular in shape, apex bluntly rounded. Labrum (Fig. 1 D) bifid posteroventral lobes elongated. Antennule (Fig. 1 F) 7 - segmented, slender, 319 μm long, with armature formula: 4, 13, 6, 3, 4 + 1 aesthetasc, 2 + 1 aesthetasc, and 7 + 1 aesthetasc; all setae smooth. Antenna (Fig. 1 G) slender, 4 - segmented, with armature formula: 1, 1, 3, and 5 + 2 claws. Approximate lengths of first to fourth segments 83, 74, 32, and 96 μm. Two terminal claws nearly equal in length, 85 μm and 110 μm. Shorter claw slightly thicker than longer. Mandible (Fig. 2 A) inner medial margin knotched, with lateral triangular process close to the distal outer margin, inner margin with dense spinule rows. Convex margin with row of minute spinules. Lash long and serrate along both margins. Maxillule (Fig. 1 H) small, 1 - segmented with 3 terminal and 1 lateral setae. Maxilla (Fig. 1 I) 2 - segmented, syncoxa (first segment) unarmed, basis (second segment) with 2 small surface setae and one inner enlarge seta, with spinules along only one margin. Distal lash longer than inner seta, evenly curved Maxilliped (Fig. 2 B) 3 - segmented. Syncoxa (first segment) longest and unarmed, basis (second segment) with two long smooth medial setae almost equal in length, short endopod (third segment) shortest, spinelike with lateral denticles and one small surface seta, and large lateral spine with denticles. Legs 1 - 4 (Fig. 2 C – E, 3 A) 3 - segmented exopod and endopod, except P 4 endopod only 2 - segmented, with following armature formula. Coxa Basis Exopod Endopod Leg 1 0 - 1 1 - 0 I- 0; I- 1; III, I, 4 0 - 1; 0 - 1; I, 5 Leg 2 0 - 1 1 - 0 I- 0; I- 1; III, I, 5 0 - 1; 0 - 2; I, II, 3 Leg 3 0 - 1 1 - 0 I- 0; I- 1; II, I, 5 0 - 1; 0 - 2; I, II, 2 Leg 4 0 - 1 1 - 0 I- 0; I- 1; II, I, 5 0 - I; II P 1 – P 3 inner coxal seta large and plumose, though P 4 this seta small and smooth. P 4 second endopodal segment 1.4 times as long as wide, two terminal spines the medial 2.3 times as long as lateral spine. Description. Adult male. Body (Fig. 3 C) smaller and narrower than female. Prosome ovate in shape, length 0.68 mm (0.67 mm – 0.68 mm) and greatest width 0.26 mm (0.25 mm – 0.26 mm) based on 4 specimens, lateral margins rounded. Urosome (Fig. 3 D) 6 - segmented, segment 1 (fifth pedigerous somite) small, 0.13 mm wide. Segment 2 (genital somite) distinctly broad, distolateral corners somewhat acute, 140 × 150 μm and somites 3 – 6, 20 × 60, 20 × 57, 18 × 54, and 20 × 57 μm, respectively. Caudal rami 15 × 20 μm, slightly wider than long. Rostrum and labrum as in female. Antennule with two additional aesthetasc on second segment and one in fourth segment. Antenna and mouthparts resembling those of female. Maxilliped (Fig. 3 F) 3 - segmented, syncoxa 36 μm long and unarmed, basis distally swollen and medial margin lined with small spinules and two surface setae, third segment smallest with very large terminal claw possessing large smooth proximal seta. P 5 (Fig. 3 E) free segment, 40 × 15 μm with two terminal setae, medial seta the smaller. P 1 – P 4 segmented and armed as in the female except for the last segment of P 1 endopod with armature of I, I, 4 (Fig. 3 G).	en	Varela, Carlos, Walter, T. Chad (2026): A new species of Acanthomolgus Humes & Stock, 1972 (Copepoda: Cyclopoida) from the Red Sea, Egypt, with an updated key to species. Zootaxa 5741 (2): 353-364, DOI: 10.11646/zootaxa.5741.2.7, URL: https://doi.org/10.11646/zootaxa.5741.2.7
03DD87A5632CFF80FF1B1D7A4969F8A4.taxon	etymology	Etymology. The species is dedicated to Arthur G. Humes, who described 730 symbiotic copepods during his career.	en	Varela, Carlos, Walter, T. Chad (2026): A new species of Acanthomolgus Humes & Stock, 1972 (Copepoda: Cyclopoida) from the Red Sea, Egypt, with an updated key to species. Zootaxa 5741 (2): 353-364, DOI: 10.11646/zootaxa.5741.2.7, URL: https://doi.org/10.11646/zootaxa.5741.2.7
03DD87A5632CFF80FF1B1D7A4969F8A4.taxon	discussion	Remarks. 48 species of Acanthomolgus are currently known (Walter & Boxshall, 2025). Members of this genus typically found associated with marine cnidarians, however, in this species no host data was available, though we assume it is not a free living species. Acanthomolgus humesi sp. nov. caudal rami as long as wide, antenna pair of long claws of similar lengths, maxilliped second segment medial setae of the same length, P 4 endopod second segment smooth lacks spines and spinules, except for terminal spines. Female genital segment with sides nonparallel. Other species of Acanthomolgus that share these characters are far from the Red Sea: A amboinensis Kim I. H, 2007 Ambon Island and A. gomumuiensis Kim I. H, 2007 Gomumu Island, both from Banda Islands, Indonesia; and A. gentilis (Humes & Ho, 1968 a) from Madagascar, all from southern and western Indian Ocean. Comparing these three species the following differences are noted. In A. amboinensis female P 5 free segment with a proximomedial margin roundly expanded; P 4 endopod second segment terminal spine equal in length to the segment; P 1 exopod first segment lateral spine longest of the three exopod segments. Whereas in A. humesi n. sp. P 5 free segment lacks a pronounced proximal expansion, P 4 endopod second segment terminal spine shorter than segment; P 1 exopod first segment lateral spine shorter and all three exopod segments spines equal in length. In A. gomumuensis, female P 5 free segment terminal longer seta extending past caudal rami, maxilla medial seta large with many large spinules along lateral margin and small spinules along medial margin, P 4 endopod second segment large distal spine equal in length to segment., Whereas in A. humesi sp. nov., female P 5 free segment terminal longer seta not extending past caudal rami, maxilla medial seta small with few spinules along lateral margin and none along medial margin, P 4 endopod second segment large distal spine much shorter in length to segment. In A. gentilis, P 4 endopod second segment large distal spine equal in length to segment, female P 5 free segment numerous lateral setae, male P 5 free segment elongate with lateral spinules. Whereas in A. humesi sp. nov, P 4 endopod second segment large distal spine much shorter in length to segment, female P 5 free segment few lateral setae, male P 5 free segment short lacking lateral spinules.	en	Varela, Carlos, Walter, T. Chad (2026): A new species of Acanthomolgus Humes & Stock, 1972 (Copepoda: Cyclopoida) from the Red Sea, Egypt, with an updated key to species. Zootaxa 5741 (2): 353-364, DOI: 10.11646/zootaxa.5741.2.7, URL: https://doi.org/10.11646/zootaxa.5741.2.7
03DD87A5632BFF8EFF1B1FAA4EB1FEE2.taxon	discussion	This key is based and modified on keys presented by Humes & Stock (1973), Humes (1973) and Stock (1975).	en	Varela, Carlos, Walter, T. Chad (2026): A new species of Acanthomolgus Humes & Stock, 1972 (Copepoda: Cyclopoida) from the Red Sea, Egypt, with an updated key to species. Zootaxa 5741 (2): 353-364, DOI: 10.11646/zootaxa.5741.2.7, URL: https://doi.org/10.11646/zootaxa.5741.2.7
