Tenupedunculus serrulatus Song & Bruce

Song, Ji-Hun, Bruce, Niel L. & Min, Gi-Sik, 2018, The first records of Stenobermuda Schultz, 1982 and Tenupedunculus Schultz, 1979 from Australia, with description of two new species from the Great Barrier Reef (Isopoda, Asellota, Stenetriidae), ZooKeys 733, pp. 1-24 : 5-8

Tenupedunculus serrulatus Song & Bruce sp. n. Figs 1, 2, 3, 4

Material examined.

All material from Capricorn Group, southern Great Barrier Reef.

Holotype.

♂ (4.2 mm), ‘Harry’s Bommie, Heron Island, 23.46053°S, 151.9293°E, 13 November 2010, reef slope, dead Acropora , 9 m, CReefs stn. HI10-002C, coll. C. Buxton (MTQ W33638).

Paratypes.

2 ♂ (4.5, 4.1 mm [dissected]), same sample as holotype, (MTQ W52903). ♀ (5.8 mm [pereopod 1 dissected]), same data as holotype (MTQ W33654). ♂ (5.1 mm [pereopod 7 dissected]), Sykes Reef west, 23.4316°S, 152.0493°E, 14 November 2010, reef slope, 27 m, CReefs stn. HI10-009F, coll. J. Reimer (MTQ W33694). 5 ♀ (3.2-5.0 mm), 1 juv. (1.5 mm), Sykes Reef west, 23.4316°S, 152.0493°E, 14 November 2010, reef slope, 27 m, CReefs stn. HI10-009F, coll. J. Reimer (MTQ W33695). 20 ♂ and ♀, same data as holotype, coll. C. Buxton, stn. HI10-002B (MTQ W33673, W33644) and HI10-002C (MTQ W33636, W33642). ♀ (3.5 mm), Lamont Reef, 23.5932°S, 152.0655°E, 16 November 2010, reef slope, dead Acropora , 9 m, CReefs stn. HI10-019B/1, coll. M. Blazewicz (MTQ W33753). 5 ♂ (3.8-5.8 mm), Heron Island, southern side 'Twin Peaks’, 23°28.357'S, 151°57.593'E, 28 November 2009, small rubble, 13-17 m CReefs stn. HI09-125F, coll. N.L. Bruce & K. Schnabel. (MTQ W52904). ♀ (5.8 mm), Heron Island 23.43238°S, 152.03375°E, 14 November 2009, CReefs stn. 018, no other data (MTQ W52905). ♂ (3.5 mm), 2 ♀ (2.8, 5.1 mm), Lamont Reef, southern side, 23°36.125'S, 152°03.152'E, 19 November 2009, coarse sand and small rubble, 9.7 m, CReefs stn. HI09-058D, coll. K. Schnabel & N.L. Bruce. (MTQ exW31591). MTQ W52906). 8 ♂ and ♀, Harry’s Canyons, Heron Reef, 23°28.389'S, 151°57.835'E, 18 November 2009, reef slope, small rubble and coarse sand, 6 m, CReefs stn HI09-045D, coll. N.L. Bruce & K. Schnabel (MTQ W52907). 2 ♂, 2 ♀, 2 imm., Sykes Reef, 23°25.929'S, 152°02.924'E, 18 November 2009, 26 m, coll. S. Smith & A. Anderson (MTQ W52908).

Non-type.

All Heron Island: north-eastern side, 20 November 2009, small rubble and sand at base of large bommies 7 m, CReefs stn HI09-064D (MTQ W31595). "The Patches" (=Mystery Bommie), 28 November 2009, rubble, mid-channel, 18 m, CReefs stn HI09-123C (MTQ W31604). "Harrys Bommie", 13 November 2010, dead coral on sandy bottom, CReefs stn HI10-002B, 10 m (MTQ W33669).

Etymology.

From combining the Latin words ‘serrula’ (serrated) and the ending of ‘marginatus’, alluding to the serrated body margins of this species.

Diagnosis

(male). Body (Fig. 1A) lateral margins with serrations. Pereonite 4 smallest. Pseudorostrum (Fig. 1C) wider than long, trapezoid-shape. Antennula (Fig. 1A, C) longer than cephalon, with ten flagellar articles. Antenna (Fig. 1A) longer than whole body length, with numerous flagellar articles. Maxilliped (Fig. 2D) endite distal margin with five fan setae. Pereopod 1 (Fig. 3A) superior carpal process distinctly long, bladelike. Uropods (Fig. 1A, H) well-developed, biramous, shorter than pleotelson; exopod shorter than endopod. Pleotelson (Fig. 4H) lateral margins with distinct notch.

Description

(male).Body (Fig. 1A) length 3.3 times maximum width. Cephalon (Fig. 1C) length 0.5 times width, 1.6 times pereonite 1 length; lateral margins straight or very weakly convex, serrate, with two setae; antennal spines rounded; lateral spines moderate, acute and serrate, longer than antennal spines; space between lateral and antennal spines evenly rounded. Eyes (Fig. 1C) with seven ommatidia, pale brown, arranged in circle. Pereonites 1-7 (Fig. 1A) lateral margin serrate, with one seta. Sternal keel (Fig. 1B) present both in males and females as anteriorly directed spines on posteriorly directed spine on pereonites 6. Pereonite 1 length 0.3 times width, 0.9 times pereonite 2 length, width 1.1 times cephalon width. Pleotelson (Figs 1A, 4H) length 0.9 times width; lateral margin serrate, with distinct notch.

Antennula (Fig. 1A, D) length 1.5 times cephalon length; article 1 length 1.6 times width, mesial margin with four short penicillate setae, distolateral margin with one large penicillate seta; article 2 length 1.8 times width, distomesial margin with one cluster of setae, including two penicillate seta, distolateral margin with one large penicillate seta and one short seta; article 3 length 2.9 times width, distomesial margin with one cluster of setae; article 4 length 0.3 times width, distomesial margin with one penicillate seta; flagellum with ten articles, one aesthetasc per article on distal nine articles.

Antenna (Fig. 1A, E, F, G) length approximately 1.5 times body length; peduncle article 1 length 0.8 times width, distolateral margin with one cluster of setae; article 2 length 0.6 times width, distal margin with two setae; article 3 length 1.1 times width, distomesial margin with two clusters of setae, mesial margin with one long seta and one short seta, lateral margin with five setae surrounding squama; article 4 length 0.7 times width, distomesial margin with three setae; article 5 length 6.8 times width; article 6 length 7.9 times width; each flagellum article with a cluster of four distally projecting setae, the cluster position serially repeating every four articles.

Mandible (Fig. 2A) left spine row with eleven spines, right spine row with six spines; palp article 1 length 2.5 times width, distolateral margin with one long seta, and two short setae; palp article 2 length 2.9 times width, with row of seven short serrate setae; article 3 length 2.6 times width. Maxillula (Fig. 2B) lateral lobe apex with 14 serrate RS; mesial lobe apex with two large plumose setae, distomesial margin with one setulate RS, one large plumose seta. Maxilla (Fig. 2C) mesial lobe mesial margin with eight large plumose setae, apex with three large setulate setae, two setae with spatulate tips; middle lobe apex with four large setulate setae; lateral lobe apex with four large setulate setae. Maxilliped (Fig. 2D) basis length 2.2 times maximum width, width 1.1 times endite width; endite distal margin with five fan setae, distomesial margin with six serrate setae, distomesial corner with two triangular RS; epipod length 3.2 times width, width 1.2 times basis width, apex acute, distomesial margin with eight regularly spaced setae, lateral margin sinuate.

Pereopod 1 (Fig. 3A) basis length 3.7 times width; superior margin with three long setae alternate with three short; submarginal row of short setae.

Pereopod 1 ischium length 1.6 times width; inferior margin with one short seta; superodistal margin produced, with eight long setae, apex acute.

Pereopod 1 merus angular; merus length 1.1 times width, 0.8 times carpus length, 0.8 times ischium length; inferior margin with one short seta, two long setae; inferior submargin with a dense patch of long setae; distal margin with no setae; superodistal margin produced, apex acute, densely setose with long setae and two short setae.

Pereopod 1 carpus triangular; length 1.5 times width, 1.1 times ischium length; distal margin convex, with two short setae; inferior margin clearly defined, and densely setose along distal two-thirds only; inferior submargin with a dense patch of short setae. Superior carpal process long, bladelike; length 3.3 times width, 1.7 times carpal width; extending distally approximately half length of propodus; apex acute, densely setose; inferior margin smooth, straight, densely setose along distal two-thirds only, with several rows of setae; superior margin slightly convex, setose along full length.

Pereopod 1 propodus robust superiorly with inferior side of article flattened; length 1.5 times maximum width, 3.6 times proximal width, 2.2 times ischium length; inferior margin clearly defined, long, 0.7 times propodus length, 0.6 times superior margin length, densely covered with rows of long and serrate setae and with submarginal row of short setae; superior margin setose, setae regularly spaced. Propodal palm (Fig. 3B) width 0.6 times maximum propodus width, slightly oblique; toothed lobe with four teeth, largest tooth length 3.0 times smallest tooth length; short setae inserting between teeth, cluster of setae at articulation and long setae on mesial surface.

Pereopod 1 dactylus robust; length 4.8 times width, 1.4 times propodal palm width, 0.9 times propodus distal width (not including process), 0.6 times propodus length; superior margin distal third setose, with regularly spaced setae; distal margin setae regularly spaced along entire length; and more sparsely distributed long setae; mesial surface sparsely setose.

Pereopod 2 (Fig. 3C) basis superior margin with three penicillate setae; ischium superior margin with one large seta; merus superodistal margin produced with one large RS at apex; carpus superodistal margin with cluster of setae, including one penicillate seta, inferior margin with four flagellated RS (most distal paired with one RS); propodus superodistal margin with cluster of setae, including one penicillate seta, inferior margin with four flagellated RS, inferodistal margin with one flagellated RS.

Pereopod 7 (Fig. 3D) basis superior margin with two penicillate setae; inferior margin without stiff setae; carpus inferior margin with two flagellated RS; propodus inferior margin with five flagellated RS, inferodistal margin with one flagellated RS.

Pleopod 1 (Fig. 4A) protopod length 0.7 times width, distal margin with pair of robust setae, surface setae absent; rami lateral margins with regularly spaced setae along distal two-thirds of margin, inferior surface without setae. Pleopod 2 (Fig. 4B) protopod length 2.6 times medial width, basal lobe width 1.8 times medial width, distal lobe distinctly shorter than exopod, distal lobe blunt; endopod length 0.6 times protopod length, without setae; appendix masculina (Fig. 4C) length 1.6 times endopod length, 0.9 times protopod length, widest distally; lateral margin without distal groove; mesial margin without setae; apex convex, depression fringed with scale setae; lateral margin without setae. Pleopod 3 (Fig. 4D) endopod apex with five plumose setae. Pleopod 4 (Fig. 4E) exopod apex with nine plumose setae. Pleopod 5 (Fig. 4F) apex with five plumose setae.

Uropod (Fig. 1A, H) length 0.2 times body length, 0.7 times pleotelson length; protopod length 2.4 times width; endopod length 1.1 times protopod length, distal and sub-distal margins with three penicillate setae, distal tip with cluster of elongate setae with maximum length 1.5 times endopod length; exopod length 0.8 times protopod length, 0.7 times endopod length, distal tip with cluster of elongate setae with maximum length 0.9 times exopod length.

Description

(female).Pereopod 1 (Fig. 3E) basis length 3.2 times width, superior margin with 12 short setae, inferior margin with six short setae. Ischium superodistal margin produced, apex acute. Merus superodistal margin produced; process apex acute. Propodus length 1.4 times distal (maximum) width, 2.8 times proximal width, 1.6 times ischium length; inferior margin length 0.7 times propodus length, densely setose, with a row of setulate setae and a row of simple setae, setae restricted to distal three-quarters of margin; propodal palm (Fig. 3F) width 0.8 times distal propodus width; straight, slightly oblique, with five teeth, inferior end with single robust flagellated seta, and single robust serrate seta adjacent to first tooth, articulation with 14 long setae. Dactylus length 5.6 times width, 1.3 times palm width, inferior margin with 17 regularly spaced robust flagellated setae, with irregularly distributed long setae.

Pleopod 2 (Fig. 4G) length 1.5 times maximum width; lateral margins with 2-5 setae; not parallel, narrowing posteriorly; posterolateral margins concave, apex slightly notched, asymmetric, with two setae; inferior surface without setae.

Size.

Males 2.6-5.1 mm (mean 3.9 mm, n = 6); females 2.3-5.8 mm (mean 3.8 mm, n = 24).

Remarks.

Tenupedunculus serrulatus sp. n. is distinguished from other species of Tenupedunculus by the following unique combination characters: merus superodistal margin with strongly produced distally rounded process, more than 3.0 times as long as wide; male pleopod 2 appendix masculina bluntly rounded apically, without apical setae; and the lateral margins of the body (from cephalon to pleotelson) are serrated.

Tenupedunculus serrulatus is most similar to the deep-water species T. pulchrum (Schultz, 1982) with regard to general external appearance, but is distinguished by the following: small body size (<6 mm vs. 9 mm for the holotype of T. pulchrum ), serrations on lateral margin of the whole body (vs. smooth); the very strongly produced process on pereopod 1 carpus superodistal margin, approximately 2.5 times as long as width of carpus proximal margin (vs. weak process, approximately 0.6 times as long as width of carpus proximal margin); and appendix masculina without any acute part (vs. with small acute part). Tenupedunculus serrulatus is the only shallow-water tropical species in the genus.

Distribution.

Heron Island and reefs of the Capricorn Group, southern Great Barrier Reef, Australia; at depths of 6-27 m.