Hoplopolemius olo Jóźwiak & Stępień, 2025

(SOSA), Senckenberg Ocean Species Alliance, Andrade, Luiz F., Boyko, Christopher B., Brandt, Angelika, Buge, Barbara, Dávila Jiménez, Yasmín, Henseler, Mats, Hernández Alcántara, Pablo, Jóźwiak, Piotr, Knauber, Henry, Marcondes Machado, Fabrizio, Martínez-Muñoz, Carlos A., Momtazi, Farzaneh, Nakadera, Yumi, Qiu, Jian-Wen, Riehl, Torben, Rouse, Greg W., Sigwart, Julia D., Sirenko, Boris, Souza-Filho, Jesser F., Steger, Jan, Stępień, Anna, Tilic, Ekin, Trautwein, Bianca, Vončina, Katarzyna, Williams, Jason D. & Zhang, Junlong, 2025, Ocean Species Discoveries 13 – 27 — Taxonomic contributions to the diversity of Polychaeta, Mollusca and Crustacea, Biodiversity Data Journal 13, pp. e 160349-e 160349 : e160349-

Hoplopolemius olo Jóźwiak & Stępień sp. nov.

Materials

Type status: Holotype. Occurrence: catalogNumber: SMF 57072 ; recordedBy: Marine Environmental Monitoring Ghana 2012; individualCount: 1; sex: female; lifeStage: adult; reproductiveCondition: ovigerous; establishmentMeans: native; occurrenceStatus: present; occurrenceID: 943DD085-468E-5C32-A894-B9C98FB4D950; Taxon: scientificName: Hoplopolemius olo Jóźwiak & Stępień ; kingdom: Animalia; phylum: Arthropoda; class: Malacostraca; order: Tanaidacea ; family: Metapseudidae ; genus: Hoplopolemius ; specificEpithet: olo ; taxonRank: species; scientificNameAuthorship: Jóźwiak & Stępień; nomenclaturalCode: ICZN; Location: higherGeography: North Atlantic Ocean; waterBody: Gulf of Guinea; country: Ghana; locality: Gulf of Guinea, station G 3 / 25 ; verbatimDepth: 28 m; verbatimLatitude: 4°45'52.9"N; verbatimLongitude: 2°07'57.7"W; decimalLatitude: 4.7647; decimalLongitude: - 2.1327; Identification: identifiedBy: Piotr Jóźwiak; dateIdentified: 2025; Event: samplingProtocol: 0.1 m ² van Veen grab, sieved throught 0.3 mm mesh; eventDate: 19 / 11 / 2012; habitat: Fine sandy mud; fieldNumber: G 3 / 26; Record Level: institutionCode: SMF; collectionCode: Crustacea; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SMF 57073 ; recordedBy: Marine Environmental Monitoring Ghana 2013; individualCount: 1; sex: female; lifeStage: preadult; reproductiveCondition: non-ovigerous; establishmentMeans: native; occurrenceStatus: present; occurrenceID: 21BB24E9-428A-5879-910F-EFEA8466AEAC; Taxon: scientificName: Hoplopolemius olo Jóźwiak & Stępień ; kingdom: Animalia; phylum: Arthropoda; class: Malacostraca; order: Tanaidacea ; family: Metapseudidae ; genus: Hoplopolemius ; specificEpithet: olo ; taxonRank: species; scientificNameAuthorship: Jóźwiak & Stępień; nomenclaturalCode: ICZN; Location: higherGeography: North Atlantic Ocean; waterBody: Gulf of Guinea; country: Ghana; locality: Gulf of Guinea, station G 3 / 25 ; verbatimDepth: 28 m; verbatimLatitude: 4°45'52.9"N; verbatimLongitude: 2°07'57.7"W; decimalLatitude: 4.7647; decimalLongitude: - 2.1327; Identification: identifiedBy: Piotr Jóźwiak; dateIdentified: 2025; Event: samplingProtocol: 0.1 m ² van Veen grab, sieved throught 0.3 mm mesh; eventDate: 19 / 11 / 2012; habitat: Fine sandy mud; fieldNumber: G 3 / 26; Record Level: institutionCode: SMF; collectionCode: Crustacea; basisOfRecord: PreservedSpecimen

Description

Ovigerous female: Habitus (Fig. 53 A, B). Body length (BL) = 4.6 mm, 5.6 times as long as wide (L: W). Ceph 1.0 L: W, 0.17 × BL, rostrum with three small teeth. Pereon 3.0 L: W, 0.6 × BL. Prn 1–6: 0.4, 0.4, 0.5, 0.6, 0.5, 0.4 L: W, respectively, each with lateral and distal setae. Pleon with Plt 0.23 × BL. Pl 1–5 same size, 0.2 L: W. Plt with rounded apex.

A 1 (Fig. 54 A): articles with simple and broom setae; art 1 5.2 L: W, 2.5 × art 2, with two apophyses on each outer and inner margin; art 2 2.3 L: W, 1.7 × art 3; art 3 2.5 L: W; acc flag with three articles; outer flag with nine articles, art 3 and art 7 with aesthetascs.

A 2 (Fig. 54 B): articles with simple and broom setae, art 1 with broad inner apophysis; art 2 3 L: W, with distal inner spine, squama with two lateral and three distal setae; art 3 0.8 L: W, with inner distal spine; art 4 and art 5 2.5 L: W each, art 4 with distal spine; flagellum with five articles.

Mouthparts. Lbr (Fig. 54 C) setose. Left md (Fig. 54 D) incisor denticulated, lacinia mobilis with two denticles, setal row of four trifurcated setae, molar broad (Fig. 54 D’); palp with three articles, each with row of plumose setae (Fig. 54 D’ ’). Right md (Fig. 54 E) incisor with four denticles, setal row of three trifurcated setae, molar broad (Fig. 54 E’). Mx 1 (Fig. 54 F) outer endite with eight terminal spines. Mx 2 (Fig. 54 G) typical for suborder. Lb (Fig. 54 H) lobe with one terminal setae; lobe and lateral margin with row of spines. Mxp (Fig. 54 I) art 1 with distal setae; art 2 with row of inner setae and one strong outer seta; art 3 and art 4 with row of inner setae, two subdistal setae on art 4. Endite (Fig. 54 I’) with row of lateral and distal setae, two subdistal setae and two coupling hooks. Epignath (Fig. 54 J).

Ch (Fig. 55 A) basis 1.5 L: W, with ventral spine; merus with ventral apophysis at mid-length; carpus 1.3 L: W; propodus palm 1.0 L: W, with two ventral apophysis and nine inner setae at the surface; fixed finger 2.0 L: W, with row of inner and ventral setae; dactylus little longer than fixed finger, with three distal setae and row of small inner spines. Exopod with four distal setae.

P 1 (Fig. 55 B) longer than the other pereopods, setose; basis with three dorsal apophysis and ventral distal spine; ischium with two setae; merus and carpus with ventral and dorsal spines distally; propodus with four spines along ventral margin and dorsal spine distally; dactylus with unguis 0.7 × propodus, dactylus with two ventral apophysis. Exopod with five setae. P 2 (Fig. 55 C) setose; basis with dorsal apophysis; merus with two ventral spines; carpus with three ventral spines; propodus with three ventral spines and dorsal spine distally; dactylus with unguis similar in length to propodus, with two ventral spines. P 3 (Fig. 55 D) similar to P 2, but carpus with four spines (three inner). P 4 (Fig. 55 E) setose; merus with two ventral spines; carpus with ventral spine and five spines (two inner) along distal margin; propodus with two ventral spines; dactylus with two ventral spines. P 5 (Fig. 55 F) similar to P 4, but merus with two inner spines and carpus with four spines (two inner). P 6 (Fig. 55 G) basis, merus and carpus with row of plumose setae along ventral and dorsal margins; propodus with row of short plumose setae along ventral and distal margin.

Plp (Fig. 55 H) biramous, five pairs, all similar; basis with two plumose setae; exopod with 14 setae; endopod with plumose 23 setae.

U (Fig. 55 I) exopod with five art; endopod (broken) with at least 22 art.

Type material

Holotype, ovigerous female ( SMF 57072) and paratype, non-ovigerous dissected on slides ( SMF 57073).

Material examined

Two specimens - holotype ( SMF 57072) and paratype ( SMF 57073).

Type locality

North-eastern tropical Atlantic Ocean, Gulf of Guinea, off Ghanaian coast, 4°45'52.9"N, 2°07'57.7"W, 28 m depth.

Diagnosis

Rostrum with three small teeth; smooth lateral margins of Plt; dorsal apophysis on basis of P 2–3.

Etymology

"Olo" in Polish is a diminutive form of Aleksander. This species is dedicated to Aleksander Jóźwiak, the beloved son of Piotr Jóźwiak and a great (and brave) companion on local and more distant field trips.

Distribution

West Africa, Gulf of Guinea.

Taxon discussion

The presence of a multi-articulate inner flagellum on the A 1, which is shorter than the outer flagellum, along with five pairs of pleopods, are key diagnostic characters of the genus Hoplopolemius , as described by Jóźwiak and Błażewicz (2021). The newly-described species represents the fourth known member of the genus and the first recorded from the East Atlantic Ocean. Hoplopolemius propinquus and H. triangulatus were previously reported from Bermuda ( Richardson 1902), while H. toyoshious was described from waters near Japan ( Larsen and Shimomura 2006).

The new species can be distinguished from its congeners by the following morphological features: (1) the rostrum, which bears three small teeth, whereas it is pointed in other species; (2) the absence of an outer distal spine or apophysis on art 1 of A 1, a feature present in other species; and (3) the structure of the cheliped, with a fixed finger bearing two ventral apophyses and the basis of P 2–3 having a dorsal apophysis. In contrast, the ventral margin of the fixed finger and the dorsal margin of the P 2–3 basis are smooth in the other three species.

Hoplopolemius olo can also be distinguished from other representatives of the subfamily Chondropodinae occurring along the West African coast, namely Calozodion pabisi Jakiel & Jóźwiak, 2015 ( Jakiel et al. 2015) and C. dominiki Bochert, 2012 ( Bochert 2012), by its three-denticulated rostrum. In C. pabisi , the rostrum is flat and multidenticulated, whereas in C. dominiki , it is triangular, wide and has smooth margins. Additionally, the new species exhibits smooth lateral margins of the pleotelson, whereas C. pabisi and C. dominiki have lateral apophyses.

Methods

The samples were collected in October and November 2012 from the Gulf of Guinea, western Africa, from the R / V DR. FRIDTJOF NANSEN, with use of a 0.1 m ² van Veen grab. The collected material was sieved through a 0.3 mm mesh and sorted in the laboratory. The paratype of Hoplopolemius was dissected with needles, mounted in glycerine on slides and sealed with melted paraffin. Illustrations were initially made using a microscope, equipped with a camera lucida and were subsequently re-drawn digitally using a graphic tablet, following the method described by Coleman (2003).

Repository: The type material is deposited at the Senckenberg Natural History Museum in Frankfurt ( SMF).

Figures

Figure 53. Hoplopolemius olo Jóźwiak & Stępień, sp. nov. Ovigerous female, holotype (SMF 57072), habitus. A Dorsal view; B Lateral view. Scale bar: 1 mm.

Figure 54. Hoplopolemius olo Jóźwiak & Stępień, sp. nov. Non-ovigerous female, paratype (SMF 57073). A Antennule; B Antenna; C Labrum; D Left mandible; D ’ Molar of left mandible; D ’’ Palp of left mandible; E Right mandible; E ’ Molar of right mandible; F Maxillule endite; G Maxilla; H Labium; I Maxilliped; I ’ Endite of maxilliped; J Epignath. Scale bars: 0.1 mm.

Figure 55. Hoplopolemius olo Jóźwiak & Stępień, sp. nov. Non-ovigerous female, paratype (SMF 57073). A Cheliped; B Pereopod 1; C Pereopod 2; D Pereopod 3; E Pereopod 4; F Pereopod 5; G Pereopod 6; H Pleopoda; I Uropoda. Scale bars: 0.1 mm.