Balucopsylla Rao, 1972

Mu, Fanghong & Huys, Rony, 2021, A new species of Helmutkunzia Wells & Rao, 1976 from an intertidal sandy beach in Xiamen, China and proposal of Pseudobalucopsylla gen. nov. (Copepoda Harpacticoida, Miraciidae), Zootaxa 5051 (1), pp. 487-505 : 498-499

Genus Balucopsylla Rao, 1972

Type species. Balucopsylla similis Rao, 1972 [by original designation].

Other species. None.

Diagnosis. Miraciidae . Diosaccinae . Body linear. Original segmentation of ♀ genital double-somite marked by dorsolateral chitinized internal ridges. Cephalothorax and all somites with plain hyaline frill and without surface ornamentation. Anal operculum present; pseudoperculum absent. Caudal ramus slightly longer than wide; with seven setae; seta I vestigial (or possibly absent); seta II long and setiform; seta III short and spiniform; seta IV distinctly shorter then seta V, without fracture plane; seta V well developed, with distinct fracture plane; seta VI short and setiform; seta VII arising from biarticulate socle.

Rostrum elongate, narrow and pointed. Antennule ♀ 8-segmented, slender, segment 2 longest, segments 5–7 small, last four segments combined only about one quarter of combined length of proximal four; with aesthetasc on segments 4 and 8. Antennule ♂ subchirocer, 9- or 10-segmented. Antenna with unarmed basis and proximal endopod segment; exopod 2-segmented, exp-1 with lateral seta, exp-2 with naked lateral seta and spiniform element apically. Mandibular palp biramous; basis with two setae; apical setae of endopod not forming pseudosegment; exopod minute, 1-segmented, with two short elements. Maxillulary exopod defined at base, with two setae; condition of endopod and basis unconfirmed. Maxilla with three endites on syncoxa; endopod 1-segmented. Maxilliped subchelate, syncoxa unarmed; basis with one seta (?); endopod an elongate segment with minutely pinnate claw and one accessory seta.

P1 with 3-segmented rami. Exp-1 and -2 without inner seta, exp-3 with two outer spines and two geniculate apical setae. Endopod longer than exopod; enp-1 elongate, with inner seta; enp-2 with inner seta; enp-3 with one spine, one geniculate seta and one minute seta. Inner margin of ♂ basis not modified; inner spine enlarged and curved.

P2–P4 with 3-segmented rami; endopod longer than (P2–P3) or about same length as (P4) exopod. Apical spinous projections on P2–P4 enp-3 long and slender. P2 endopod ♂ not modified. Armature pattern as follows:

P 5 ♀ exopod elongate, with five setae; endopodal lobe apical margin with two setae, inner margin with two setiform elements. P 5 ♂ exopod with five setae; baseoendopods not medially fused, endopodal lobes weakly developed, each with two setiform elements apically.

Genital field ♀ with paired gonopores each closed off by vestigial P6 bearing two setae, inner one very long and naked. P 6 ♂ represented by symmetrical opercula each bearing three naked setae, middle one longest.

Paired egg-sacs.

Notes. Balucopsylla differs from Pseudobalucopsylla gen. nov. in the following aspects: (a) hyaline frills of all body somites plain (vs genital double-somite and abdominal somites 2–3 in ♀ and abdominal somites 1–3 in ♂ with finely semi-incised subulate frill), (b) caudal ramus seta I vestigial or possibly absent (vs very well developed, almost as long as seta II and displaced to midventral position), (c) caudal ramus seta IV much shorter than seta V, without fracture plane (vs well developed with distinct fracture plane); (d) antennule ♂ subchirocer, aesthetasc-bearing segment distinctly swollen (vs haplocer), (e) antennary exopod 2-segmented (vs 3-segmented), (f) mandibular basis with two setae (vs three), (g) mandibular exopod minute, 1-segmented, with two setae (vs well developed, 2-segmented, with 4–5 setae), (h) apical setae of mandibular endopod discrete at base (vs confluent at base, forming minute pseudosegment), (i) maxillipedal syncoxa unarmed (vs with 2–3 setae), (j) P1 basis not modified in ♂ (vs inner margin heavily chitinized and with large unguiform projection in ♂), (k) apical spinous projections on P2–P4 enp-3 long and slender (vs small or of moderate size and not slender), (l) P2–P3 enp-3 with inner seta (vs without inner seta), (m) inner margin of P5 endopodal lobe ♀ with two naked setiform elements (vs with massive, pectinate or smooth, proximal spine and bipinnate, spiniform or setiform, distal element), (n) baseoendopods not medially fused (vs fused medially, forming common plate), and (o) P 6 ♀ with two elements (vs with three elements) .

Some of Rao’s (1972) observations require confirmation while others are undoubtedly wrong. For example, it is unclear whether caudal ramus seta I is genuinely absent or vestigial; his lateral view ( Fig. 2C ) definitely confirms that it is not developed to the same extent as in members of Pseudobalucopsylla gen. nov. The male antennule was figured as 8-segmented and described as chirocer. It is conceivable that the minute fourth and sixth segments were overlooked; the presence of three segments distal to the geniculation in conjunction with the swollen aesthetascbearing segment indicate that it is of the subchirocer type. The extremely reduced maxillulary palp shows only a bisetose exopod and two setiform elements around its apex; it is likely that the endopod and some of the basal elements were overlooked. Rao’s illustration of the maxilla is almost certainly inaccurate, showing only one element on each of the syncoxal endites (instead of a 2,2,3 pattern) and an allobasis with “… five unguiform spines”. Re-examination will probably reveal that some of these “spines” belong to (the proximal segment of) the endopod which was depicted by Rao as a minute bisetose segment. The unarmed condition of the syncoxa and the presence of only one palmar seta on the basis (the proximal one is missing) of the maxilliped also require confirmation.

Balucopsylla similis has only been reported once since its original discovery in Visakhapatnam in Andhra Pradesh. Rao (1989) recorded it further north in the Bay of Bengal , in Puri and the Bahuda estuary, in Odisha (formerly Orissa) State; he gave a body length range of 560–580 μm but did not specify the sex .

Figures

FIGURE 2. Helmutkunzia xiamenensis sp. nov. (♀): (A) antennule (armature omitted); (B) antennule (disarticulated) showing armature; (C) antenna; (D) labrum; (E) mandible (gnathobase shown in inset); (F) maxillule (coxal endite shown in inset); (G) maxilla; (H) maxilliped; (I) P1, anterior.